These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

TEMPORARY CAPTURE OF PLANETESIMALS BY A PLANET FROM THEIR HELIOCENTRIC ORBITS  

SciTech Connect

When planetesimals encounter a planet, they can be temporarily captured by the planet's gravity and orbit about it for an extended period of time before escaping from the planet's vicinity. Such a process may have played an important role in the origin of irregular satellites or the dynamical evolution of short-period comets. Using three-body orbital integration, we study the temporary capture of planetesimals by a planet from their heliocentric eccentric orbits. We examine the dependence of the orbital characteristics during temporary capture as well as the rate of capture on the pre-capture heliocentric orbital parameters. We find that typical orbital size and direction of revolution around the planet change depending on planetesimals' initial eccentricity and energy. When initial eccentricity is so small that Kepler shear dominates the relative velocity between planetesimals and the planet, temporary capture typically occurs in the retrograde direction in the vicinity of the planet's Hill sphere, while large retrograde capture orbits outside the Hill sphere are predominant for large eccentricities. Long prograde capture occurs in a very narrow range of planetesimal eccentricity and energy. We obtain the rate of temporary capture of planetesimals and find that the rate of long capture increases with increasing eccentricity at low and high eccentricities, but decreases with increasing eccentricity in intermediate values of eccentricity. We also examine the dependence of capture rate on the duration of capture and find an approximate power-law dependence.

Suetsugu, Ryo; Ohtsuki, Keiji [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan); Tanigawa, Takayuki, E-mail: ryo3088@stu.kobe-u.ac.jp [Center for Planetary Science, Kobe University, Kobe 650-0047 (Japan)

2011-12-15

2

Lessons Learned from Natural Space Debris in Heliocentric Orbit: An Analogue for Hazardous Debris in Earth Orbit  

NASA Astrophysics Data System (ADS)

Interplanetary Field Enhancements (IFEs) were discovered almost 30 years ago in the PVO magnetic-field records. Our current understanding is that IFEs result from interactions between solar wind and clouds of nanometer-scale charged dust released in interplanetary collisions. These charged dust clouds are then accelerated by the solar wind and moving away from the Sun at near solar wind speed and detected by spacecraft in heliocentric orbit. The dynamics of the debris in heliocentric orbit is analogous to that mankind has placed into Earth orbit. There are lessons here that are worth exploring. The IFE formation hypothesis was supported by the discovery of co-orbiting materials associated with asteroid 2201 Oljato: IFE rate peaked when Oljato was close and IFE occurrence clustered in the longitudes near which the orbit of Oljato intersects the orbital plane of Venus. A followed up study with Venus Express observations suggested that the co-orbiting materials dissipated in 30 years. An important aspect of this evolution is that at collisional speeds of 20 km/s, a small body can destroy one 106 times more massive. This destruction of large debris by small debris could also be important in the evolution of the terrestrial debris. At 1AU, based on ACE and Wind observations, IFEs have a significant cluster in the longitude range between 195° and 225°. Thus we use the same IFE technique to identify the ‘parent’ Near-Earth Objects of co-orbiting materials which should be responsible for those IFEs. There are more than 5000 JPL documented NEOs whose ecliptic plane crossings are near to or inside the Earth’s orbit and whose orbital periods are less than five years. By comparing their trajectories, we find that the asteroid 138175 is a good candidate for the ‘parent’ body. This asteroid orbits the Sun in a 5.24° inclined elliptical orbit with a period of 367.96 days. Its descending node is at about 206°, where the IFE occurrence rate peaks. We also find that there is a spread of the IFE rate around the descending node, indicating that the co-orbiting materials have significant dispersion about the asteroid’s orbit. In summary, orbiting debris in orbits intersecting at high speeds can destroy itself quite efficiently, but with a long timescale. In deep space, this process is a step on the path between the asteroidal source population and the creation of solar system dust. This may be true for Earth-orbiting debris as well.

Russell, C. T.; Wei, Hanying; Connors, Martin; Lai, Hairong; Delzanno, Gian Luca

3

Probes to the inferior planets—A new dawn for NEO and IEO detection technology demonstration from heliocentric orbits interior to the earth's?  

NASA Astrophysics Data System (ADS)

Recent years have seen a renewed interest in exploration of the interior of the solar system. A number of missions are currently under way, in planning as well as in space, with the primary goal to expand our knowledge on the planets Mercury and Venus. Chemical propulsion missions to Mercury in particular require an extended cruise phase prior to arrival at their destination, usually involving multiple planetary fly-by manoeuvres and many revolutions in heliocentric orbit. The difficulties in discovering and tracking small objects interior to Earth's orbit, mainly due to unfavourable viewing geometry as well as atmospheric interference, have long been noted by the solar system science and planetary defence communities. Space probes in the interior of the solar system are in a position to observe objects near or interior to Earth's orbit in favourable opposition geometry. They are also usually free from planet-related interference, at least while in cruise, and often can be while in planetary eclipse. Dedicated search and survey missions to look for Near and Inner Earth Objects (NEO, IEO) from the vicinity of Earth or low Earth orbit are being planned. In this article, the ad-hoc available as well as near-term planned in-situ capabilities of the optical instrument payloads of space probes to Venus and Mercury are compiled from publications by the respective instrument teams. The small-object detection capabilities of cameras and spectrographs in opposition geometry are estimated by a common method, using data from comparable instruments to supplement missing information where necessary. The on-board cameras are classified according to their small-object detection potential in a technology demonstration of asteroid detection from a heliocentric orbit substantially interior to Earth's.

Grundmann, Jan Thimo; Mottola, Stefano; Drentschew, Maximilian; Drobczyk, Martin; Kahle, Ralph; Maiwald, Volker; Quantius, Dominik; Zabel, Paul; van Zoest, Tim

2013-09-01

4

Simulations of the Solar Orbiter spacecraft interactions with the Solar wind at different heliocentric distances: effects on SWA-EAS measurements  

NASA Astrophysics Data System (ADS)

This presentation focuses on numerical simulations of the Solar Orbiter spacecraft/plasma interactions performed with the Spacecraft Plasma Interaction System (SPIS) software (http://dev.spis.org/projects/spine/home/spis/). This toolkit aims at modelling spacecraft-plasma interactions, based on an electrostatic 3-D unstructured particle-in-cell plasma model. New powerful SPIS functionalities were recently delivered within the extension of the software: SPIS-Science (ESA contract). This version revolutionizes spacecraft/plasma interactions as users are now able to model and configure plasma instrument such as Langmuir probes or particle detectors taking into account instrument characteristics like geometry, materials, energy ranges and resolution, output frequency, field of view ... In the validation context of SPIS-Science functionalities, a simulation campaign was carried out, including several cases of the ESA Solar Orbiter mission. The results presented here specifically focus on particle measurements through the modelling of the Solar Wind Analyzer - Electron Analyzer System instrument (SWA-EAS). Simulations of the spacecraft in different environments have been performed and extensively analysed. A detailed analysis will be presented concerning 1/ the satellite charging and, in particular, differential potentials on the dielectric surfaces of the Solar panels and the High Gain Antenna, which may severely affect low energy EAS measurements, 2/ the surrounding plasma behaviour : potential barriers for secondary and photoelectrons of about -5 V around the vehicle are indeed observed at the mission perihelion of 0.28 AU from the Sun and 3/ a quantification of biases on EAS measurements due to the combined effects of surface potentials, ion wake, and potential barriers. This work proposes a general framework to prepare the analysis of the future Solar Orbiter measurements.

Guillemant, S.; Genot, V. N.; Matéo Vélez, J.; Sarrailh, P.; Louarn, P.; Maksimovic, M.; Owen, C. J.; Hilgers, A. M.

2013-12-01

5

Ancient Greek Heliocentric Views Hidden from Prevailing Beliefs?  

NASA Astrophysics Data System (ADS)

We put forward the working hypothesis that the heliocentric, rather than the geocentric view, of the Solar System was the essential belief of the early Greek philosophers and astronomers. Although most of them referred to the geocentric view, it is plausible that the prevalent religious beliefs about the sacred character of the Earth as well as the fear of prosecution for impiety (asebeia) prevented them from expressing the heliocentric view, even though they were fully aware of it. Moreover, putting the geocentric view forward, instead, would have facilitated the reception of the surrounding world and the understanding of everyday celestial phenomena, much like the modern presentation of the celestial sphere and the zodiac, where the Earth is at the centre and the Sun makes an apparent orbit on the ecliptic. Such an ingenious stance would have set these early astronomers in harmony with the dominant religious beliefs and, at the same time, would have helped them to 'save the appearances', without sacrificing the essence of their ideas. In Hellenistic and Roman times, the prevailing view was still the geocentric one. The brilliant heliocentric theory advanced by Aristarchos in the early third century B.C. was never established, because it met with hostility in Athens - Aristarchos was accused of impiety and faced the death penalty. The textual evidence suggests that the tight connection which existed between religion and the city-state (polis) in ancient Greece, and which led to a series of impiety trials against philosophers in Athens during the fifth and fourth centuries B.C., would have made any contrary opinion expressed by the astronomers seem almost a high treason against the state.

Liritzis, Ioannis; Coucouzeli, Alexandra

2008-03-01

6

Planar heliocentric roto-translatory motion of a spacecraft with a solar sail of complex shape  

Microsoft Academic Search

A complete treatment of the general motion of rotation and translation of a solar-sail spacecraft is proposed for the non-flat sail of complex shape. The planar heliocentric roto-translatory motion is considered, orbit-rotational coupling in the problem of altitude and orbital sail motion is investigated for the two-folding sail formed by two unequal reflective rectangular plates oriented at a right angle.

S. N. Kirpichnikov; E. S. Kirpichnikova; E. N. Polyakhova; A. S. Shmyrov

1995-01-01

7

Analytical control laws of the heliocentric motion of the solar sail spacecraft  

NASA Astrophysics Data System (ADS)

The heliocentric motion of the solar sail spacecraft is described in classical Keplerian elements. The flat of solar sail with an ideal reflection coefficient is considered. The spacecraft performs a noncoplanar motion with the sun gravity and the light pressure. Disturbances of other celestial bodies gravity are not considered. We have received analytical terms for laws to control a solar sail, which ensure constancy or maximum rate of change of the Keplerian elements. To confirm the results correctness, we simulated the solar sail spacecraft. The spacecraft's initial orbit coincides with the average Earth orbit relative to the Sun. Authors developed a program complex to simulated the planar heliocentric movement and obtained results for motion simulation of flights to Mars and Venus. The results were compared with the simulation results obtained using the Pontryagin maximum principle.

Gorbunova, Irina; Starinova, Olga

2014-12-01

8

Statistical analysis of micrometeoroids at the heliocentric distance of Mercury  

NASA Astrophysics Data System (ADS)

This work shows preliminary results of a study of the orbital evolution of dust particles originating from the Main Belt in order to obtain a statistical analysis, then to provide an estimate of the flux of particles hitting the Mercury's surface. We can distinguish two population of meteoroids depending on their dynamical evolution: small particles (r < 1 cm) dominated by the Poynting-Robertson drag, and large particles (r > 1 cm) driven by gravity only. In this work we consider small particles and, in particular, the micrometeoroids produced by collisional fragmentation of cometary or asteroidal bodies. The main effects that determine the distribution of dust in the Solar System are the gravitational attractions of the Sun and planets, Poynting-Robertson drag, solar radiation pressure, solar wind pressure and the effects of different magnetic fields. In order to determine the meteoritic flux at the heliocentric distance of Mercury we utilize the dynamical evolution model of dust particles of Marzari and Vanzani (1994) that numerically solves a (N+1)+M body problem (Sun + N planets + M body with zero mass) with the high-precision integrator RA15 (Everhart 1985). The solar radiation pressure and Poynting-Robertson drag, together with the gravitational interactions of the planets, are taken as major perturbing forces affecting the orbital evolution of the dust particles. We will perform numerical simulations with different initial conditions for the dust particles, depending on the sources, with the aim of estimating to flux of dust on the surface of Mercury. Meteoroid impacts have a very important role in the evolution of Mercury's surface and exosphere. Since the exobase is presently on the surface of the planet, the sources and sinks of the exosphere are tightly linked to the composition and structure of the planet surface. We intend also to evaluate a possible asymmetry between the leading and trailing surface of Mercury in terms of impact frequency.

Borin, P.; Cremonese, G.; Marzari, F.

2007-08-01

9

Proof-of-Concept Trajectory Designs for a Multi-Spacecraft, Low-Thrust Heliocentric Solar Weather Buoy Mission  

NASA Technical Reports Server (NTRS)

A new solar weather mission has been proposed, involving a dozen or more small spacecraft spaced at regular, constant intervals in a mutual heliocentric circular orbit between the orbits of Earth and Venus. These solar weather buoys (SWBs) would carry instrumentation to detect and measure the material in solar flares, solar energetic particle events, and coronal mass ejections as they flowed past the buoys, serving both as science probes and as a radiation early warning system for the Earth and interplanetary travelers to Mars. The baseline concept involves placing a mothercraft carrying the SWBs into a staging orbit at the Sun-Earth L1 libration point. The mothercraft departs the L1 orbit at the proper time to execute a trailing-edge lunar flyby near New Moon, injecting it into a heliocentric orbit with its perihelion interior to Earth s orbit. An alternative approach would involve the use of a Double Lunar Swingby (DLS) orbit, rather than the L1 orbit, for staging prior to this flyby. After injection into heliocentric orbit, the mothercraft releases the SWBs-all equipped with low-thrust pulsed plasma thrusters (PPTs)-whereupon each SWB executes a multi-day low-thrust finite bum around perihelion, lowering aphelion such that each achieves an elliptical phasing orbit of different orbital period from its companions. The resulting differences in angular rates of motion cause the spacecraft to separate. While the lead SWB achieves the mission orbit following an insertion burn at its second perihelion passage, the remaining SWBs must complete several revolutions in their respective phasing orbits to establish them in the mission orbit with the desired longitudinal spacing. The complete configuration for a 14 SWB scenario using a single mothercraft is achieved in about 8 years, and the spacing remains stable for at least a further 6 years. Flight operations can be simplified, and mission risk reduced, by employing two mothercraft instead of one. In this scenario: the second mothercraft stays in a libration-point or DLS staging orbit until the first mothercraft has achieved nearly 180 separation from the Earth. The timing of the second mothercraft's subsequent lunar flyby is planned such that this spacecraft will be located 180 from the first mothercraft upon completion of its heliocentric circularization maneuvers. Both groups of satellites then only have to spread out over 180 to obtain full 360 coverage around the Sun.

Muller, Ronald; Franz, Heather; Roberts, Craig; Folta, Dave

2005-01-01

10

Solar wind stream structure at large heliocentric distances Pioneer observations  

NASA Technical Reports Server (NTRS)

Time profiles and histograms of plasma data from Pioneers 10 and 11 are examined for the period between 1975 and 1983. During this time, Pioneer 10 traveled between a heliocentric distance of 8.7 and 30.4 AU. The velocity structure of the solar wind at these heliocentric distances is found to have one of two distinct forms: approximately 70 percent of the time the solar wind has a nearly flat velocity profile. Occasionally, this flat velocity profile is accompanied by quasi-periodic variations in density and in thermal speed consistent with the concept that the 'corotating interaction regions' which are produced by the interaction of high- and low-speed streams at intermediate heliocentric distances are replaced by 'pressure regions' in the outer heliosphere. The remaining 30 percent of the time the solar wind is marked by large (50-200 km/s) long-term (30-120 days) shifts in the average solar wind velocity.

Gazis, P. R.

1987-01-01

11

Back to the Future: The Return to Heliocentrism  

E-print Network

to the Sun, p2 = a3 #12;Galileo Galilei (1564-1642) · The first experimental physicist? ­ Demonstrated stars in the Milky Way #12;#12;#12;#12;Galileo vs. the Pope · The Catholic Church was not anti, heliocentric cosmology · But Galileo insulted Pope Urban VIII in his book Dialogue Concerning the Two Chief

Walter, Frederick M.

12

CCD-photometry of comets at large heliocentric distances  

NASA Technical Reports Server (NTRS)

CCD imaging and time series photometry are used to determine the state of activity, nuclear properties and eventually the rotational motion of cometary nuclei. Cometary activity at large heliocentric distances and mantle evolution are not yet fully understood. Results of observations carried out at the 2.1 telescope on Kitt Peak April 10-12 and May 15-16, 1991 are discussed. Color values and color-color diagrams are presented for several comets and asteroids. Estimations of nuclear radii and shapes are given.

Mueller, Beatrice E. A.

1992-01-01

13

Heliocentric distance dependence of the interplanetary magnetic field  

NASA Technical Reports Server (NTRS)

Recent and ongoing planetary missions have provided extensive observations of the variations of the Interplanetary Magnetic Field (IMF) both in time and with heliocentric distance from the sun. Large time variations in both the IMF and its fluctuations were observed. These are produced predominantly by dynamical processes in the interplanetary medium associated with stream interactions. Magnetic field variations near the sun are propagated to greater heliocentric distances, also contributing to the observed variablity of the IMF. Temporal variations on a time-scale comparable to or less than the corotation period complicate attempts to deduce radial gradients of the field and its fluctuations from the various observations. However, recent measurements inward to 0.46 AU and outward to 5 AU suggest that the radial component of the field on average decreases approximately as r to the minus second power, while the azimuthal component decreases more rapidly than the r to the minum first power dependence predicted by simple theory. This, and other observations, are discussed.

Behannon, K. W.

1977-01-01

14

Orbits  

NSDL National Science Digital Library

This Topic in Depth explores the Web's offerings on Orbits. The first site is offered by Northwestern University and asks: What is an orbit? (1 ). The site answers questions such as What causes an orbit to happen?, What is a satellite?, What travels in an orbit?, and Are there orbits within orbits?. A great starting site for this subject, visitors should come away with a broad and clear description of the topic. The second site, called Orbit Diagrams (2 ) is provided by the Harvard-Smithsonian Center for Astrophysics. The diagrams are "intended to aid in the visualization of the three-dimensional nature of the orbits and how they are orientated with respect to the orbit of the earth." Next, from the University of Wisconsin-Madison Department of Astronomy comes the Moon Phases (3 ) interactive Web site. Users are able to animate the moon's orbit in various phases and views as well as learn all the names of the phases. The fourth site is another virtual visualization tool provided by NASA's Near Earth Object Program called Orbits (4 ). The site lets users enter the designation or name of any asteroid or comet and then view the three-dimensional orbit of that object. The next site, maintained by the Conservation, Astronomy, Physics and Soaring Page, is called Satellite Orbits - Gravitational Assist from Planets (5 ). The site contains information on Kepler's Laws, which apply to elliptical orbits involving two bodies, hyperbolic orbits, relative motion, and the gravitational sphere of influence. The sixth site is an educational lesson provided by Dr. Richard L. Bowman of Bridgewater College called Planetary Orbit Exercise (6 ). Students are given information on Keplar's Laws of Planetary Motion, a list of definitions, links to outside sites for additional information, and then several questions to answer. The Planetary Physical Data (7 ) page is part of the larger Smithsonian Center for Earth and Planetary Studies Web site. Visitors will find a list of planets along with various information such as their relative sidereal period of orbit, mean orbital velocity, orbital eccentricity, and much more. The last site related to orbits is an educational activity provided by the Physics Classroom called Circular Motion and Planetary Motion (8 ). Four lessons are presented including Motion Characteristics for Circular Motion, Applications of Circular Motion, Universal Gravitation, and Planetary and Satellite Motion. Each contain clear and well written descriptions along with all the necessary information for successful completion.

Brieske, Joel A.

15

Microlens Masses from 1-D Parallaxes and Heliocentric Proper Motions  

NASA Astrophysics Data System (ADS)

One-dimensional (1-D) microlens parallaxes can be combined with heliocentric lens-source relative proper motion measurements to derive the lens mass and distance, as suggested by Ghosh et al. (2004). Here I present the first mathematical anlysis of this procedure, which I show can be represented as a quadratic equation. Hence, it is formally subject to a two-fold degeneracy. I show that this degeneracy can be broken in many cases using the relatively crude 2-D parallax information that is often available for microlensing events. I also develop an explicit formula for the region of parameter space where it is more difficult to break this degeneracy. Although no mass/distance measurements have yet been made using this technique, it is likely to become quite common over the next decade.

Gould, Andrew

2014-12-01

16

Heliocentric zoning of the asteroid belt by aluminum-26 heating  

NASA Astrophysics Data System (ADS)

The dependence of asteroid spectral class (and inferred composition and thermal history) on heliocentric radius has been held to be the result of heating by a solar energy source, most likely electrical induction, during the formation of the planetary system. Such variations in thermal history can be more simply explained by the presence of different amounts of the radionuclide aluminum-26, whose decay products are observed in meteorites, in planetesimals. These differences occurred naturally as a function of the increasing amount of time required to accrete objects farther from the sun, during which aluminum-26 decayed from its initial concentration in the solar nebula. Both theory and isotopic evidence suggest that increases in accretion time across the asteroid belt are of order several half-lives of aluminum-26, which is sufficient to produce the inferred differences in thermal history.

Grimm, R. E.; McSween, H. Y.

1993-01-01

17

67P/Churyumov-Gerasimenko: start of activity and heliocentric light curve  

NASA Astrophysics Data System (ADS)

Comets are believed to be widely unmodified remnants from the formation of the solar system; their study can give important insights into the conditions prevailing at the time of the planetary system formation. After the success of the Giotto mission to comet 1P/Halley, the European Space Agency (ESA) approved in the early nineties a new space mission with a comet as main target: Rosetta, which will rendezvous with come 67P/Churyumov-Gerasimenko (67P/C-G) in 2014. 67P/C-G is a Jupiter family comet with orbital period of 6.56 years. Due to repeated encounters with Jupiter, the orbital evolution of 67P/C-G is chaotic. The last encounter in February 1959 occurred at a distance of only 0.0518 AU and produced drastic changes in perihelion distance, eccentricity, inclination, orbital period and possibly led to its discovery in 1969. After 67P/C-G was selected as target comet of Rosetta mission, observational campaigns and theoretical investigations were performed in order to establish a detailed portrait of 67P/C-G in preparation of the rendezvous with the spacecraft ([1], [2], [3], [4]). Here we present ground-based observations of 67P/CG obtained between July 2007 and March 2008 at ESO VLT using the FORS2 instrument. The comet was moving inbound, from 4.6 AU to 3.4 AU. The orbital arc covered by our observation is the same where 67P/C-G will be in 2014 when the rendezvous with the Rosetta spacecraft will take place, thus of highly interest for mission planning. Since the comet's activity around perihelion has shown similar behaviour during the last three orbital passages, it is fair to assume that the comet's behavior at large heliocentric distance has not changed from one orbital revolution to the other, leading us to expect that during its approach to 67P/CG, Rosetta will find the same conditions detected during our observations. A considerable difficulty in observing 67P/C-G during the past years has been its position against crowded fields towards the galactic centre for much of this time (Fig. 1 - top). The 2007/8 data presented here was particularly difficult, and the comet will once again be badly placed for Earth based observations in 2014/5. We made use of the technique of Difference Image Analysis (as implemented in the DanDIA software, [5]), which is commonly used in variable star and exoplanet research, to remove background sources and extract images of the comet (Fig. 1 - bottom). We determined that the comet became active during the period November 2007 - March 2008, at a distance of 4.1-3.4 AU from the Sun. The comet will reach this distance, and probably become active again, in April- September 2014. To investigate the longer period activity cycle of the comet we compiled the heliocentric light curve of the comet, making use of images of 67P/C-G taken during the last three apparitions taken from the ESO archive. A preliminary light curve is shown in 2. This information will be used for planning observing campaigns, both from the ground and using OSIRIS on board Rosetta.

Tubiana, C.; Snodgrass, C.; Bramich, D.; Boehnhardt, H.; Barrera, L.

2012-09-01

18

Heliocentric variation of dust production in comets inferred from infrared observations  

NASA Astrophysics Data System (ADS)

The observed infrared emission from comets has been used to derive the heliocentric dependence of the dust production rate. There is a tight relation with heliocentric distance r, showing 1/r-squared variation up to r less than about 1 AU for Comet Kohoutek and 1/r to the 4th for r greater than about 1 AU for Comet Halley. There appears to be a general pattern of behavior in the shape of the heliocentric dependence of the dust production rate for several comets. This trend is qualitatively similar to the sublimation curves for water-ice.

Krishna Swamy, K. S.

1991-01-01

19

New estimate of the micrometeoroids flux at the heliocentric distance of Mercury  

NASA Astrophysics Data System (ADS)

This work shows preliminary results of a study of the orbital evolution of dust particles originating from the Main Belt in order to obtain a statistical analysis, then to provide an estimate of the flux of particles hitting the Mercury's surface. Meteoritic flux on Mercury really depends on the particle size, because meteoroids of different size follow different dynamical evolution. In this work we consider meteoritic sizes smaller than 1 cm that are particles with a dynamical evolution dominated by the Poynting-Robertson effect. The meteoroid impact mechanism seems to be an important source of neutral atoms contributing to the exosphere and, according to recent papers, mostly due to particles smaller than 1 cm. Unfortunately the dynamical studies and statistics of meteoroids smaller than 1 cm are based on quite old papers and always extrapolated from calculations made for the Earth. This is the reason why we are working on a dynamical model following small dust particles that may hit the surface of Mercury. Up to now we have taken into account only particles coming from the Main Belt. The main effects that determine the distribution of dust in the Solar System are the gravitational attractions of the Sun and planets, Poynting-Robertson drag, solar radiation pressure, solar wind pressure and the effects of different magnetic fields. In order to determine the meteoritic flux at the heliocentric distance of Mercury we utilize the dynamical evolution model of dust particles of Marzari and Vanzani (1994) that numerically solves a (N+1)+M body problem (Sun + N planets + M body with zero mass) with the high-precision integrator RA15 (Everhart 1985). The solar radiation pressure and Poynting-Robertson drag, together with the gravitational interactions of the planets, are taken as major perturbing forces affecting the orbital evolution of the dust particles. We have performed numerical simulations with different initial conditions for the dust particles, depending on the sources, with the aim of estimating to flux of dust on the surface of Mercury. In this work we will report the first interesting estimate of the flux of small particles, and their velocity distribution, hitting the surface of Mercury. We intend also to evaluate a possible asymmetry between the leading and trailing surface of Mercury in terms of impact frequency.

Borin, Patrizia; Cremonese, Gabriele; Marzari, Francesco

20

No evidence for a decrease of nuclear decay rates with increasing heliocentric distance based on radiochronology of meteorites  

NASA Astrophysics Data System (ADS)

It has been argued that the decay rates of several radioactive nuclides are slightly lower at Earth's aphelion than at perihelion, and that this effect might depend on heliocentric distance. It might then be expected that nuclear decay rates be considerably lower at larger distances from the sun, e.g., in the asteroid belt at 2-3 AU from where most meteorites originate. If so, ages of meteorites obtained by analyses of radioactive nuclides and their stable daughter isotopes might be in error, since these ages are based on decay rates determined on Earth. Here we evaluate whether the large data base on nuclear cosmochronology offers any hint for discrepancies which might be due to radially variable decay rates. Chlorine-36 (t1/2 = 301,000 a) is produced in meteorites by interactions with cosmic rays and is the nuclide for which a decay rate dependence from heliocentric distance has been proposed, which, in principle, can be tested with our approach and the current data base. We show that compilations of 36Cl concentrations measured in meteorites offer no support for a spatially variable 36Cl decay rate. For very short-lived cosmic-ray produced radionuclides (half-lives < 10-100 days), the concentration should be different for meteorites hitting the Earth on the incoming vs. outgoing part of their orbit. However, the current data base of very short-lived radionuclides in freshly fallen meteorites is far from sufficient to deduce solid constraints. Constraints on the age of the Earth and the oldest meteorite phases obtained by the U-Pb dating technique give no hints for radially variable decay rates of the ?-decaying nuclides 235U or 238U. Similarly, some of the oldest phases in meteorites have U-Pb ages whose differences agree almost perfectly with respective age differences obtained with "short-lived" radionuclides present in the early solar system, again indicating no variability of uranium decay rates in different meteorite parent bodies in the asteroid belt. Moreover, the oldest U-Pb ages of meteorites agree with the main-sequence age of the sun derived from helioseismology within the formal ˜1% uncertainty of the latter. Meteorite ages also provide no evidence for a decrease of decay rates with heliocentric distance for nuclides such as 87Rb (decay mode ?-) 40K (?- and electron capture), and 147Sm (?).

Meier, Matthias M. M.; Wieler, Rainer

2014-03-01

21

From Pythagoreans to Kepler: the dispute between the geocentric and the heliocentric systems  

NASA Astrophysics Data System (ADS)

Some ancient Greek philosophers and thinkers questioned the geocentric system and proposed instead a heliocentric system. The main proponents of this view - which was seen as heretical at the time - are believed to have been the Pythagoreans Philolaos, Heraclides, Hicetas, and Ecphantos, but mainly Aristarchos of Samos, who placed the Sun in the position of the "central fire" of the Pythagoreans. The geocentric system, reworked by Claudius Ptolemaeus (Ptolemy), was the dominant one for centuries, and it was only during the sixteenth century that the Polish monk-astronomer, Copernicus, revisited the ancient Greek heliocentric views and became the new champion of the theory that we all accept today.

Theodossiou, E.; Danezis, E.; Manimanis, V. N.; Kalyva, E.-M.

2002-06-01

22

Interest of old data for the determination of the heliocentric distance of Pluto  

E-print Network

53 Interest of old data for the determination of the heliocentric distance of Pluto L. Beauvalet1, 75014 Paris, France Abstract Pluto was discovered in 1930. It is also the multiple system which has been known for the longest time with the discovery of its first satellite Charon in 1978. Because of Pluto

23

The trend of production rates with heliocentric distance for comet P/Halley  

NASA Astrophysics Data System (ADS)

Comet P/Halley was observed spectroscopically in the wavelength range 5200-10,400 A during 10 observing runs, roughly a month apart from 1985 August 28 to 1986 June 6. The observations span a heliocentric distance from 0.73 to 2.52 AU. This data set is analyzed to determine the course of the production rate with heliocentric distance for C2, NH2, CN, and the continuum. The effect of changing the Haser scale lengths and their heliocentric distance dependence is examined. The production rate ratios to water change only in a minor way, but the absolute values of the production rates are more severely affected. Fluorescent efficiencies, or g-factors for the CN red system are calculated, and band intensity ratios for NH2 and CN are presented. Using presently available fluorescence efficiencies and Haser scale lengths, mixing ratios for the parents of C2, CN, and NH2 with respect to water are: 0.34 +/- 0.07%, 0.15 +/- 0.04%, and 0.13 +/- 0.05%. It is found that these mixing ratios are essentially constant over the heliocentric distance range of the observations, implying a rather uniform nucleus and uniform outgassing characteristics, although there are indications of smaller scale day-to-day variations. The results provide strong observational confirmation that water evaporation controls the activity of the comet over the distance range studied. Continuum values Af rho are determined, and their ratios to QH2O are found to have a clear dependence with heliocentric distance approximately r-1.0 with a post-perihelion enhancement. No correlation of the production rate ratios with light curve of P/Halley were found, nor was there any correlation of the C2 or CN production with the dust.

Fink, U.

1994-03-01

24

The heliocentric evolution of cometary infrared spectra - Results from an organic grain model  

NASA Technical Reports Server (NTRS)

An emission feature peaking near 3.4 microns that is typical of C-H stretching in hydrocarbons and which fits a simple, two-component thermal emission model for dust in the cometary coma, has been noted in observations of Comets Halley and Wilson. A noteworthy consequence of this modeling is that, at about 1 AU, emission features at wavelengths longer than 3.4 microns come to be 'diluted' by continuum emission. A quantitative development of the model shows it to agree with observational data for Comet Halley for certain, plausible values of the optical constants; the observed heliocentric evolution of the 3.4-micron feature thereby furnishes information on the composition of the comet's organic grains.

Chyba, Christopher F.; Sagan, Carl; Mumma, Michael J.

1989-01-01

25

Telemetry coding study for the international magnetosphere explorers, mother/daughter and heliocentric missions. Volume 2: Final report  

NASA Technical Reports Server (NTRS)

A convolutional coding theory is given for the IME and the Heliocentric spacecraft. The amount of coding gain needed by the mission is determined. Recommendations are given for an encoder/decoder system to provide the gain along with an evaluation of the impact of the system on the space network in terms of costs and complexity.

Cartier, D. E.

1973-01-01

26

A Synoptic Analysis of the Change from the Geocentric to the Heliocentric Conception of the Solar System.  

ERIC Educational Resources Information Center

The changes which occurred in man's view of the solar system from the time of Ptolemy to that of Galileo are presented. Contained is a brief review of the chain of events which resulted in the acceptance of a heliocentric system. Ptolomy's theory is described and a diagram illustrates the paths of the epicycle of Mars according to his geocentric…

Wilson, Roosevelt L.

27

Orbits from Two Observations  

NASA Astrophysics Data System (ADS)

Recent years have seen a particular interest in estimating orbital elements and ephemeris uncertainties from just two astrometric observations. Since 1996 the Minor Planet Center has used a two-observation method in which the coordinate system is rotated so that the reference plane passes through the two observations and the origin is at one of them. The selection of appropriate values for the topocentric distance ? at the other observation then immediately provides, not only the components of the heliocentric position vector, but also two components of the heliocentric velocity vector. It therefore remains to select appropriate values for the third velocity component, the value zero yielding ?, the largest reciprocal semimajor axis for the specified ?. The Vaisala (or apsidal) value of the velocity component follows, together with values yielding the two lateral orbits (at most one of which can be elliptical), with the object on the orbital latus rectum. If ? is positive, elliptical solutions exist for values of the velocity component out to ±??. It is also the case that ? generally decreases with increasing ?, though not necessarily monotonically. Indeed, for an object at opposition, distances corresponding to a lone parabolic solution readily follow from a cubic equation, there being one or three real roots according as to whether the apparent retrograde motion is greater than or less than some critical value. A very similar quadratic equation can be used to derive the distances corresponding to precisely circular solutions, when the apsidal velocity component is equal to the smaller of the lateral values. Corresponding equations are also derived to describe possible orbits near quadrature.

Marsden, Brian G.

2010-05-01

28

A numerical comparison with the Ceplecha analytical meteoroid orbit determination method  

E-print Network

A numerical comparison with the Ceplecha analytical meteoroid orbit determination method David L accepted 11 May 2011) Abstract­Analytic methods by Ceplecha have long been used for the determination of meteoroid heliocentric orbits. These methods include both the derivation of an initial atmospheric contact

Wiegert, Paul

29

Radiants, velocities, and orbital elements of meteoroid particles of the Perseid shower according to image-converter measurements  

NASA Astrophysics Data System (ADS)

The paper presents a catalog of radiants, velocities, and heliocentric-orbit elements for 27 Perseid meteor particles obtained from image-converter observations. The upper values for variations of the orbital elements in the shower are obtained together with the limits of radiant coordinate variations.

Shafiev, R. I.; Andreev, G. V.; Mukhamednazarov, S.

30

Study of the Forbidden Oxygen Lines in Comets at Different Heliocentric and Nucleocentric Distances  

NASA Astrophysics Data System (ADS)

Oxygen is an important element in the chemistry of the solar system objects given its abundance and its presence in many molecules including H2O 80% of cometary ices). The analysis of oxygen atoms in comets can provide information not only on the comets themselves but also on the solar system. These atoms have been analyzed using the 3 forbidden oxygen lines [OI] observed in emission in the optical region at 5577.339 Å (the green line), 6300.304 Å and 6363.776 Å (the red lines) (Swings, 1962). Our analysis is based on a sample of 12 comets of various origins. The observing material is made of 53 high signal-to-noise spectra obtained with the high-resolution UVES spectrograph at the ESO VLT from 2002 to 2012 (Manfroid et al, 2009). After noticing that the green line is blended with one C2 line, we built synthetic spectra of C2 for each observing circumstances and we subtracted its contribution to the cometary spectra in order to ensure the decontamination of the 5577 Å line. Then, we measured the intensity of the 3 [OI] lines at different heliocentric distances. By comparing the green to red lines ratio (G/R) with the Bhardwaj & Raghuram (2012) effective excitation rates, we found that H2O is the main parent molecule when the comet is observed at 1 au. When the comet is located beyond 2.5 au from the Sun, CO2 also contributes to the production of oxygen. Studying forbidden oxygen lines could be a new way to estimate the abundances of CO2 in comets, a very difficult task from the ground (Decock et al. 2013). In order to estimate the effect of the quenching on our results, we analyzed the evolution of the G/R ratio at different nucleocentric distances. For nearby comets, we divided the extended 2D spectrum into several zones in order to analyze the oxygen lines as close as possible to the nucleus (down to ~10 km for the closest comets). Their analysis will allow us to study the link of the oxygen lines with the nucleocentric distance. We found a clear variation of the G/R ratio close to the comet nucleus that is in agreement with a contribution from CO2 as predicted by Raghuram & Bhardwaj (2013).

Decock, Alice; Rousselot, P.; Jehin, E.; Hutsemékers, D.; Manfroid, J.; Bhardwaj, A.; Raghuram, S.

2013-10-01

31

A survey on orbital dynamics and navigation of asteroid missions  

NASA Astrophysics Data System (ADS)

Asteroid exploration is currently one of the most concerned topics among international space agencies. Orbital dynamics and navigation are obviously crucial for asteroid exploration. This paper aims to give a brief review on the dynamics, control and navigation of asteroid reconnaissance orbits, including the heliocentric transfer orbit and near asteroid orbit. The developments in optimization techniques of the transfer segment are discussed in detail. We surveyed global researches in this field and made comments on several important progresses. The final section proposed a prospective of future studies with emphasis on the key techniques of these issues in the asteroid exploration missions.

Baoyin, He-Xi; Li, Jun-Feng

2014-06-01

32

Possible Periodic Orbit Control Maneuvers for an eLISA Mission  

NASA Technical Reports Server (NTRS)

This paper investigates the possible application of periodic orbit control maneuvers for so-called evolved-LISA (eLISA) missions, i.e., missions for which the constellation arm lengths and mean distance from the Earth are substantially reduced. We find that for missions with arm lengths of 106 km and Earth-trailing distance ranging from approx. 12deg to 20deg over the science lifetime, the occasional use of the spacecraft micro-Newton thrusters for constellation configuration maintenance should be able to essentially eliminate constellation distortion caused by Earth-induced tidal forces at a cost to science time of only a few percent. With interior angle variation kept to approx. +/-0:1deg, the required changes in the angles between the laser beam pointing directions for the two arms from any spacecraft could be kept quite small. This would considerably simplify the apparatus necessary for changing the transmitted beam directions.

Bender, Peter L.; Welter, Gary L.

2012-01-01

33

Data catalog series for space science and applications flight missions. Volume 1A: Brief descriptions of planetary and heliocentric spacecraft and investigations  

NASA Technical Reports Server (NTRS)

Planetary and heliocentric spacecraft, including planetary flybys and probes, are described. Imaging, particles and fields, ultraviolet, infrared, radio science and celestial mechanics, atmospheres, surface chemistry, biology, and polarization are discussed.

Cameron, W. S. (editor); Vostreys, R. W. (editor)

1982-01-01

34

Photochemistry of atomic oxygen green and red-doublet emissions in comets at larger heliocentric distances  

NASA Astrophysics Data System (ADS)

Context. In comets, the atomic oxygen green (5577 Å) to red-doublet (6300, 6364 Å) emission intensity ratio (G/R ratio) of 0.1 has been used to confirm H2O as the parent species producing forbidden oxygen emission lines. The larger (>0.1) value of G/R ratio observed in a few comets is ascribed to the presence of higher CO2 and CO relative abundances in the cometary coma. Aims: We aim to study the effect of CO2 and CO relative abundances on the observed G/R ratio in comets observed at large (>2 au) heliocentric distances by accounting for important production and loss processes of O(1S) and O(1D) atoms in the cometary coma. Methods: Recently we have developed a coupled chemistry-emission model to study photochemistry of O(1S) and O(1D) atoms and the production of green and red-doublet emissions in comets Hyakutake and Hale-Bopp. In the present work we applied the model to six comets where green and red-doublet emissions are observed when they are beyond 2 au from the Sun. Results: The collisional quenching of O(1S) and O(1D) can alter the G/R ratio more significantly than that due to change in the relative abundances of CO2 and CO. In a water-dominated cometary coma and with significant (>10%) CO2 relative abundance, photodissociation of H2O mainly governs the red-doublet emission, whereas CO2 controls the green line emission. If a comet has equal composition of CO2 and H2O, then ~50% of red-doublet emission intensity is controlled by the photodissociation of CO2. The role of CO photodissociation is insignificant in producing both green and red-doublet emission lines and consequently in determining the G/R ratio. Involvement of multiple production sources in the O(1S) formation may be the reason for the observed higher green line width than that of red lines. The G/R ratio values and green and red-doublet line widths calculated by the model are consistent with the observation. Conclusions: Our model calculations suggest that in low gas production rate comets the G/R ratio greater than 0.1 can be used to constrain the upper limit of CO2 relative abundance provided the slit-projected area on the coma is larger than the collisional zone. If a comet has equal abundances of CO2 and H2O, then the red-doublet emission is significantly (~50%) controlled by CO2 photodissociation and thus the G/R ratio is not suitable for estimating CO2 relative abundance.

Raghuram, Susarla; Bhardwaj, Anil

2014-06-01

35

Orbit Determination and Navigation of the Solar Terrestrial Relations Observatory (STEREO)  

NASA Technical Reports Server (NTRS)

This paper provides an overview of the required upgrades necessary for navigation of NASA's twin heliocentric science missions, Solar TErestrial RElations Observatory (STEREO) Ahead and Behind. The orbit determination of the STEREO spacecraft was provided by the NASA Goddard Space Flight Center's (GSFC) Flight Dynamics Facility (FDF) in support of the mission operations activities performed by the Johns Hopkins University Applied Physics Laboratory (APL). The changes to FDF's orbit determination software included modeling upgrades as well as modifications required to process the Deep Space Network X-band tracking data used for STEREO. Orbit results as well as comparisons to independently computed solutions are also included. The successful orbit determination support aided in maneuvering the STEREO spacecraft, launched on October 26, 2006 (00:52 Z), to target the lunar gravity assists required to place the spacecraft into their final heliocentric drift-away orbits where they are providing stereo imaging of the Sun.

Mesarch, Michael A.; Robertson, Mika; Ottenstein, Neil; Nicholson, Ann; Nicholson, Mark; Ward, Douglas T.; Cosgrove, Jennifer; German, Darla; Hendry, Stephen; Shaw, James

2007-01-01

36

Gravity and Orbits: Orbits  

NSDL National Science Digital Library

This Science Object is the third of three Science Objects in the Gravity and Orbits SciPack. It provides an understanding of how gravitational forces influence the motion of an object in orbit. When a force acts toward a single center, an object's forward motion and its motion toward that center can combine to create a curved path around the center. Gravity governs the motion of all objects in the solar system. The Sun's gravitational pull holds the Earth and other planets in their orbits, just as the planets' gravitational pull keeps their moons in orbit around them. Learning Outcomes:? Describe the conditions that would lead an object into orbital motion in terms of the effects of gravitational force.? Explain how an object orbits a planet in terms of trajectories and free fall.? Identify gravity as the force that keeps the planets in their orbits around the Sun and the moons in their orbits around the planets.

National Science Teachers Association (NSTA)

2006-11-01

37

Organic ices in the coma of comet C/2012 S1 (ISON) at heliocentric distances greater than 4 AU?  

NASA Astrophysics Data System (ADS)

Comet C/2012 S1 (ISON) was monitored during its approach to the inner solar system, when the comet passed from a heliocentric distance of 6.0 to 4.3 AU. As many other Oort cloud comets at their first approach to the Sun, also comet ISON exhibited a systematic over population of grains in the inner part of the coma, as revealed by the ?Af function (Tozzi et al., 2007, A&A 476, 979). So far this effect has been interpreted as due either to a short timescale variation of activity (outbursts), or long timescale variation of activity associated with very low escape velocity of the grains or with sublimating grains. In the presentation we will show that the most likely explanation of the phenomena is the sublimation of icy CO2 grains. We will discuss also the implication of CO2 production rates by this distributed source on the whole gas production rates of the comet at so large heliocentric distances.

Tozzi, Gian-Paolo; Faggi, Sara; Brucato, John R.; Bruni, Ivan; Licandro, Javier; Mazzotta Epifani, Elena; Meech, Karen; Mottola, Stefano; Watanabe, Makoto

2014-11-01

38

Probing Solar System History with Orbits, Masses, and Colors of Transneptunian Binaries  

Microsoft Academic Search

The recent discovery of numerous transneptunian binaries TNBs opens a window into dynamical conditions in the protoplanetary disk where they formed as well as the history of subsequent events which sculpted the outer Solar System and emplaced them onto their present day heliocentric orbits. To date, at least 47 TNBs have been discovered, but only about a dozen have had

William Grundy

2007-01-01

39

Program manual for HILTOP, a heliocentric interplanetary low thrust trajectory optimization program. Part 1: User's guide  

NASA Technical Reports Server (NTRS)

A performance-analysis computer program, that was developed explicitly to generate optimum electric propulsion trajectory data for missions of interest in the exploration of the solar system is presented. The program was primarily designed to evaluate the performance capabilities of electric propulsion systems, and in the simulation of a wide variety of interplanetary missions. A numerical integration of the two-body, three-dimensional equations of motion and the Euler-Lagrange equations was used in the program. Transversality conditions which permit the rapid generation of converged maximum-payload trajectory data, and the optimization of numerous other performance indices for which no transversality conditions exist are included. The ability to simulate constrained optimum solutions, including trajectories having specified propulsion time and constant thrust cone angle, is also in the program. The program was designed to handle multiple-target missions with various types of encounters, such as rendezvous, stopover, orbital capture, and flyby. Performance requirements for a variety of launch vehicles can be determined.

Mann, F. I.; Horsewood, J. L.

1974-01-01

40

Orbital evolution modeling of Damocloides  

NASA Astrophysics Data System (ADS)

In this paper we performed the task of orbital evolution modeling for 93 currently known Damocloids, 1 Gyr backward and forward in time, using the integration package SWIFTER. The package includes seven integration technics. We choosed the SyMBA integrator (Symplectic Massive Body Algorithm), which allows to handle close approaches between test particles and planets. We included the Sun, the eight planets, and Pluto as massive bodies in our simulation. The initial state vectors for test particles and planets were taken from HORIZONS JPL service. The timestep of integration was 7.305 days. The calculations were stopped when the particle reached heliocentric distance 5000 AU. The value is close to the inner boundary of the Oort cloud. It is shown, that dynamical lifetime of the population is about 1-10 myr. We present the Damocloids orbital parameters distributions and discuss the results of the simulation for Damocloids inclinations changes with time. Our results show that the dynamic lifetime of Damocloids population is about 106-107 years. Population of Damocloids retains highly inclined orbits during the integration time into the past and into the future. Thus, the population of Damocloids may indeed represent the dynamical relationship of comets on inclined orbits (Halley-type comets) with a hypothetical spherical Oort Cloud. Some of evolutionary tracks allow transition from retrograde motion to direct and vice versa (e.g.Dioretsa asteroid (20461)). However, for large periods of time, due to close encounters with the giant planets, the simulation results should be considered only statistically.

Guliyev, Rustam; Churyumov, Klim; Kovalenko, Nataliya

41

Constraining the Dust Coma Properties of Comet C/Siding Spring (2013 A1) at Large Heliocentric Distances  

E-print Network

The close encounter of Comet C/2013 A1 (Siding Spring) with Mars on October 19, 2014 presented an extremely rare opportunity to obtain the first flyby quality data of the nucleus and inner coma of a dynamically new comet. However, the comet's dust tail potentially posed an impact hazard to those spacecraft. To characterize the comet at large heliocentric distances, study its long-term evolution, and provide critical inputs to hazard modeling, we imaged C/Siding Spring with the Hubble Space Telescope when the comet was at 4.58, 3.77, and 3.28 AU from the Sun. The dust production rate, parameterized by the quantity Af$\\rho$, was 2500, 2100, and 1700 cm (5000-km radius aperture) for the three epochs, respectively. The color of the dust coma is 5.0$\\pm$0.3$\\%$/100 nm for the first two epochs, and 9.0$\\pm$0.3$\\%$/100 nm for the last epoch, and reddens with increasing cometocentric distance out to ~3000 km from the nucleus. The spatial distribution and the temporal evolution of the dust color are most consistent wi...

Li, Jian-Yang; Kelley, Michael S P; Farnham, Tony L; A'Hearn, Michael F; Mutchler, Max J; Lisse, Carey M; Delamere, W Alan

2014-01-01

42

A STUDY OF THE HELIOCENTRIC DEPENDENCE OF SHOCK STANDOFF DISTANCE AND GEOMETRY USING 2.5D MAGNETOHYDRODYNAMIC SIMULATIONS OF CORONAL MASS EJECTION DRIVEN SHOCKS  

SciTech Connect

We perform four numerical magnetohydrodynamic simulations in 2.5 dimensions (2.5D) of fast coronal mass ejections (CMEs) and their associated shock fronts between 10 Rs and 300 Rs. We investigate the relative change in the shock standoff distance, {Delta}, as a fraction of the CME radial half-width, D {sub OB} (i.e., {Delta}/D {sub OB}). Previous hydrodynamic studies have related the shock standoff distance for Earth's magnetosphere to the density compression ratio (DR; {rho} {sub u}/{rho} {sub d}) measured across the bow shock. The DR coefficient, k {sub dr}, which is the proportionality constant between the relative standoff distance ({Delta}/D {sub OB}) and the compression ratio, was semi-empirically estimated as 1.1. For CMEs, we show that this value varies linearly as a function of heliocentric distance and changes significantly for different radii of curvature of the CME's leading edge. We find that a value of 0.8 {+-} 0.1 is more appropriate for small heliocentric distances (<30 Rs) which corresponds to the spherical geometry of a magnetosphere presented by Seiff. As the CME propagates its cross section becomes more oblate and the k {sub dr} value increases linearly with heliocentric distance, such that k {sub dr} = 1.1 is most appropriate at a heliocentric distance of about 80 Rs. For terrestrial distances (215 Rs) we estimate k {sub dr} = 1.8 {+-} 0.3, which also indicates that the CME cross-sectional structure is generally more oblate than that of Earth's magnetosphere. These alterations to the proportionality coefficients may serve to improve investigations into the estimates of the magnetic field in the corona upstream of a CME as well as the aspect ratio of CMEs as measured in situ.

Savani, N. P. [University Corporation for Atmospheric Research (UCAR), Boulder, CO 80307 (United States); Shiota, D. [Computational Astrophysics Laboratory, Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kusano, K. [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601 (Japan); Vourlidas, A. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Lugaz, N., E-mail: neel.savani02@imperial.ac.uk [Experimental Space Plasma Group, University of New Hampshire, Durham, NH 03824 (United States)

2012-11-10

43

Nuclear-electric reusable orbital transfer vehicle  

NASA Technical Reports Server (NTRS)

To help determine the systems requirements for a 300-kWe space nuclear reactor power system, a mission and spacecraft have been examined that utilize electric propulsion supported by the nuclear reactor's power for multiple transfers of cargo between low earth orbit (LEO) and geosynchronous earth orbit (GEO). A propulsion system employing ion thrusters and xenon propellant was selected. Propellant and thrusters are replaced after each sortie to GEO. The mass of the orbital transfer vehicle (OTV), empty and dry, is 11,000 kg; nominal propellant load is 5000 kg. The OTV operates between a circular orbit at 925-km altitude, 28.5-deg inclination, and GEO. Cargo is brought to the OTV by Shuttle and an orbital maneuvering vehicle (OMV); the OTV then takes it to GEO. The OTV can also bring cargo back from GEO for transfer by OMV to the Shuttle. OTV propellant is resupplied, and the ion thrusters are replaced, by the OMV before each sortie to GEO. At the end of mission life, the OTV's electric propulsion is used to place it in a heliocentric orbit so that the reactor will not return to earth. The nominal cargo capability to GEO is 6000 kg, with a transit time of 120 days; 1350 kg can be transferred in 90 days, and 14,300 kg in 240 days. These capabilities can be considerably increased by using separate Shuttle launches to bring up propellant and cargo or by changing to mercury propellant.

Jaffe, Leonard D.

1988-01-01

44

Pupils Produce their Own Narratives Inspired by the History of Science: Animation Movies Concerning the Geocentric-Heliocentric Debate  

NASA Astrophysics Data System (ADS)

In this paper, we present the design and application of a teaching scenario appropriate for 12-years-old pupils in the primary school aiming to a better understanding of scientific concepts and scientific methods, linking the development of individual thinking with the development of scientific ideas and facilitating a better understanding of the nature of science. The design of the instructional material supporting this scenario has been based on the study of the history of astronomy and especially on: (a) The various theories concerning the movement of Earth, our solar system and the universe. (b) Key-stories highlighting the evolutionary character of scientific knowledge as well as the cultural interrelations of science and society. The design of the teaching scenario has focused on the participation of pupils in gradually evolving discourses and practices encouraging an appreciation of aspects of the nature of science (e.g. the role of observation and hypothesis, the use of evidence, the creation and modification of models). In this case, pupils are asked to produce their own narratives: animation movies concerning the geocentric-heliocentric debate inspired by the history of science, as the animation technique presents strong expressional potential and currently has many applications in the field of educational multimedia. The research design of this current case study has been based on the SHINE research model, while data coming from pupils' animation movies, questionnaires, interviews, worksheets, story-boards and drawings have been studied and analyzed using the GNOSIS research model. Elaborated data coming from our analysis approach reveal the appearance, transformation and evolution of aspects of nature of science appreciated by pupils and presented in their movies. Data analysis shows that during the application pupils gradually consider more and more the existence of multiple answers in scientific questions, appreciate the effect of culture on the way science functions and the way scientists work as well as the effect of new scientific interpretations that replace the old ones in the light of new evidence. The development of pupils' animation movies carrying aspects of the history of astronomy with a strong focus on the understanding of the nature of science creates a dynamic educational environment that facilitates pupils' introduction to a demanding teaching content (e.g. planet, model, retrograde motion) placing it in context (key-stories from the history of science) and at the same time offers to pupils the opportunity to engage their personal habits, interests and hobbies in the development of their science movies.

Piliouras, Panagiotis; Siakas, Spyros; Seroglou, Fanny

2011-07-01

45

Data catalog series for space science and applications flight missions. Volume 1B: Descriptions of data sets from planetary and heliocentric spacecraft and investigations  

NASA Technical Reports Server (NTRS)

The main purpose of the data catalog series is to provide descriptive references to data generated by space science flight missions. The data sets described include all of the actual holdings of the Space Science Data Center (NSSDC), all data sets for which direct contact information is available, and some data collections held and serviced by foreign investigators, NASA and other U.S. government agencies. This volume contains narrative descriptions of planetary and heliocentric spacecraft and associated experiments. The following spacecraft series are included: Mariner, Pioneer, Pioneer Venus, Venera, Viking, Voyager, and Helios. Separate indexes to the planetary and interplanetary missions are also provided.

Horowitz, Richard (compiler); Jackson, John E. (compiler); Cameron, Winifred S. (compiler)

1987-01-01

46

Low cost transfer into useful sun-synchronous orbits at Mars  

NASA Technical Reports Server (NTRS)

Mars oblateness has been found to provide sun-synchronous orbits, including orbits with stationary apsides, similar to those used at earth. A low mass and low data rate complement of scientific instruments placed in such orbits can provide exciting planetary investigations such as the Mars Orbiter Water Mission described herein. Use of a modest Shuttle kickstage (PAM-A) and existing spacecraft hardware makes this mission low-cost. A preliminary mission and spacecraft design is described. The major emphasis of the paper is on the mechanics of heliocentric transfer for the 1986 and 1988 launch opportunities, Martian sun-synchronous orbit geometries, injectable mass capabilities, and methods of achieving these scientifically useful orbits.

Glickman, R. E.; Stuart, J. R.

1981-01-01

47

Physical properties and orbital stability of the Trojan asteroids  

NASA Astrophysics Data System (ADS)

All the Trojan asteroids orbit about the Sun at roughly the same heliocentric distance as Jupiter. Differences in the observed visible reflection spectra range from neutral to red, with no ultra-red objects found so far. Given that the Trojan asteroids are collisionally evolved, a certain degree of variability is expected. Additionally, cosmic radiation and sublimation are important factors in modifying icy surfaces even at those large heliocentric distances. We search for correlations between physical and dynamical properties, we explore relationships between the following four quantities; the normalised visible reflectivity indexes ( S), the absolute magnitudes, the observed albedos and the orbital stability of the Trojans. We present here visible spectroscopic spectra of 25 Trojans. This new data increase by a factor of about 5 the size of the sample of visible spectra of Jupiter Trojans on unstable orbits. The observations were carried out at the ESO-NTT telescope (3.5 m) at La Silla, Chile, the ING-WHT (4.2 m) and NOT (2.5 m) at Roque de los Muchachos observatory, La Palma, Spain. We have found a correlation between the size distribution and the orbital stability. The absolute-magnitude distribution of the Trojans in stable orbits is found to be bimodal, while the one of the unstable orbits is unimodal, with a slope similar to that of the small stable Trojans. This supports the hypothesis that the unstable objects are mainly byproducts of physical collisions. The values of S of both the stable and the unstable Trojans are uniformly distributed over a wide range, from 0%/1000 Å to about 15%/1000 Å. The values for the stable Trojans tend to be slightly redder than the unstable ones, but no significant statistical difference is found.

Melita, M. D.; Licandro, J.; Jones, D. C.; Williams, I. P.

2008-06-01

48

[Orbital inflammation].  

PubMed

Orbital inflammation is a generic term encompassing inflammatory pathologies affecting all structures within the orbit : anterior (involvement up to the posterior aspect of the globe), diffuse (involvement of intra- and/or extraconal fat), apical (involvement of the posterior orbit), myositis (involvement of only the extraocular muscles), dacryoadenitis (involvement of the lacrimal gland). We distinguish between specific inflammation and non-specific inflammation, commonly referred to as idiopathic inflammation. Specific orbital inflammation corresponds to a secondary localization of a "generalized" disease (systemic or auto-immune). Idiopathic orbital inflammation corresponds to uniquely orbital inflammation without generalized disease, and thus an unknown etiology. At the top of the differential diagnosis for specific or idiopathic orbital inflammation are malignant tumors, represented most commonly in the adult by lympho-proliferative syndromes and metastases. Treatment of specific orbital inflammation begins with treatment of the underlying disease. For idiopathic orbital inflammation, treatment (most often corticosteroids) is indicated above all in cases of visual loss due to optic neuropathy, in the presence of pain or oculomotor palsy. PMID:25455557

Mouriaux, F; Coffin-Pichonnet, S; Robert, P-Y; Abad, S; Martin-Silva, N

2014-12-01

49

Elliptical Orbits  

NSDL National Science Digital Library

This resource provides a textual explanation as well as animated illustration of elliptical orbits with different eccentricities. It also shows how the Sun is at the focus of an ellipse, and some of the math behind elliptical orbits. Beginner, intermediate and advanced versions of the content are available.

Roberta Johnson

2000-07-01

50

The Hot Orbit: Orbital Cellulitis  

PubMed Central

Orbital cellulitis is an uncommon condition previously associated with severe complications. If untreated, orbital cellulitis can be potentially sight and life threatening. It can affect both adults and children but has a greater tendency to occur in the pediatric age group. The infection most commonly originates from sinuses, eyelids or face, retained foreign bodies, or distant soources by hematogenous spread. It is characterized by eyelid edema, erythema, chemosis, proptosis, blurred vision, fever, headache, and double vision. A history of upper respiratory tract infection prior to the onset is very common especially in children. In the era prior to antibiotics, vision loss from orbital cellulitis was a dreaded complication. Currently, imaging studies for detection of orbital abcess, the use of antibiotics and early drainage have mitigated visual morbidity significantly. The purpose of this review is to describe current investigative strategies and management options in the treatment of orbital cellulitis, establish their effectiveness and possible complications due to late intervention. PMID:22346113

Chaudhry, Imtiaz A.; Al-Rashed, Waleed; Arat, Yonca O.

2012-01-01

51

Space-based Search for Transiting Exoplanets Orbiting Bright Stars  

NASA Astrophysics Data System (ADS)

At the current stage of research transiting planets hold the key to advancing our knowledge of exoplanets as they are the only targets that allow determination of many of the key plane-tary parameters. Because the employed techniques are differential (either photometry or spec-troscopy) and the planet is significantly fainter the host star the dominant limitation is simply the number of photons. This puts a very high premium on transiting planets with bright parent stars. The ExoPlanet Task Force recognized the high value of planets transiting bright stars and identified the need to perform a wide area space-based transit survey. In this presentation I will describe a program that addresses the ExoPTF recommendation by using the output of one of the instruments on the currently operating space mission STEREO. STEREO is the third mission in NASA's Solar Terrestrial Probes program. It uses two nearly identical spacecrafts -one on an Earth-leading orbit and one on an Earth-trailing orbit -each equipped with a suit of five small telescopes to provide a stereoscopic view of the coronal mass ejections (CME) as they propagate away from the Sun. As each of these telescopes observes a portion of the heliospehre, they also image the star field in the background. For the purposes of this study we will consider only the images obtained by the HI-1 instruments. Other instruments, although showing the stellar background as well, do not have the data output suitable for a search for transiting exoplanets. This project described here has the potential of delivering a number of very high value targets for follow-up studies with a wide range of facilities, both ground-based and space-based. It will provide a complete survey of all bright stars (<10m) for 18% of the sky. The photometric data series have the sensitivity to detect all transiting hot-Jupiters and other gas giants with periods up to ˜20 days and even some Neptune size planets orbiting bright and/or late type stars. On the extreme bright end, the survey is sensitive to some super-Earth size planets, but the available number of target stars is small. In my presentation I will describe the capabilities and limitations of the project, will demon-strate the utility of the HI-1 images for searching for transiting exoplanets, and will describe the existing data for several RV discovered planets.

Tsvetanov, Zlatan

52

Orbital shrinking  

E-print Network

Jul 12, 2011 ... ... computational experiments on the tightness and solution speed of this ... variables expressing variable sums within each orbit are introduces and used to ..... limit marks an exceeded time limit of 1800 sec.s, while boldface ...

liberti

53

Orbital Decompression  

MedlinePLUS

... appearance. One of the most common indications is Graves’ disease, an autoimmune disorder that primarily affects the thyroid gland and the eye. If the eye is affected (Grave’s orbitopathy), there is an enlargement of the orbital ...

54

Orbital Dynamics  

NSDL National Science Digital Library

This video from SpaceTEC National Aerospace Technical Education Center explains the mechanics of orbital dynamics and Newton's first law of motion. This three minute video is one of the aerospace certification readiness courses.

2011-07-27

55

Orbital debris  

NASA Astrophysics Data System (ADS)

The hazard to spacecraft posed by artificial debris in orbit, though still low, is growing and requires international attention, according to a new National Research Council (NRC) report. What's more, the problem needs to be addressed while it is still manageable, the report says. First, the NRC report suggests that spacefaring nations work together make better spacecraft hazard assessments by filling in data gaps on the effects of collisions between orbiting objects and on the amount and sources of debris in orbit. Other steps include making spacecraft designers more aware of protection methods. While removal of existing debris from orbit is technically and economically infeasible, according to the report, international efforts should focus on preventive measures.

56

W-reps, nilp orbits, orbit method  

E-print Network

W-reps, nilp orbits, orbit method David Vogan Representation theory irr reps nilp orbits irr reps W reps nilp orbits W reps Explaining the arrows Remembrance of things past Weyl group representations, nilpotent orbits, and the orbit method David Vogan Department of Mathematics Massachusetts

Vogan, David

57

Nuclear reactor power for an electrically powered orbital transfer vehicle  

SciTech Connect

To help determine the systems requirements for a 300-kWe space nuclear reactor power system, a mission and spacecraft have been examined which utilize electric propulsion and this nuclear reactor power for multiple transfers of cargo between low earth orbit (LEO) and geosynchronous earth orbit (GEO). A propulsion system employing ion thrusters and xenon propellant was selected. Propellant and thrusters are replaced after each sortie to GEO. The mass of the Orbital Transfer Vehicle (OTV), empty and dry, is 11,000 kg; nominal propellant load is 5000 kg. The OTV operates between a circular orbit at 925 km altitude, 28.5 deg inclination, and GEO. Cargo is brought to the OTV by Shuttle and an Orbital Maneuvering Vehicle (OMV); the OTV then takes it to GEO. The OTV can also bring cargo back from GEO, for transfer by OMV to the Shuttle. OTV propellant is resupplied and the ion thrusters are replaced by the OMV before each trip to GEO. At the end of mission life, the OTV's electric propulsion is used to place it in a heliocentric orbit so that the reactor will not return to earth. The nominal cargo capability to GEO is 6000 kg with a transit time of 120 days; 1350 kg can be transferred in 90 days, and 14,300 kg in 240 days. These capabilities can be considerably increased by using separate Shuttle launches to bring up propellant and cargo, or by changing to mercury propellant.

Jaffe, L.; Beatty, R.; Bhandari, P.; Chow, E.; Deininger, W.; Ewell, R.; Fujita, T.; Grossman, M.; Kia, T.; Nesmith, B.

1987-05-01

58

Nuclear reactor power for an electrically powered orbital transfer vehicle  

NASA Technical Reports Server (NTRS)

To help determine the systems requirements for a 300-kWe space nuclear reactor power system, a mission and spacecraft have been examined which utilize electric propulsion and this nuclear reactor power for multiple transfers of cargo between low earth orbit (LEO) and geosynchronous earth orbit (GEO). A propulsion system employing ion thrusters and xenon propellant was selected. Propellant and thrusters are replaced after each sortie to GEO. The mass of the Orbital Transfer Vehicle (OTV), empty and dry, is 11,000 kg; nominal propellant load is 5000 kg. The OTV operates between a circular orbit at 925 km altitude, 28.5 deg inclination, and GEO. Cargo is brought to the OTV by Shuttle and an Orbital Maneuvering Vehicle (OMV); the OTV then takes it to GEO. The OTV can also bring cargo back from GEO, for transfer by OMV to the Shuttle. OTV propellant is resupplied and the ion thrusters are replaced by the OMV before each trip to GEO. At the end of mission life, the OTV's electric propulsion is used to place it in a heliocentric orbit so that the reactor will not return to earth. The nominal cargo capability to GEO is 6000 kg with a transit time of 120 days; 1350 kg can be transferred in 90 days, and 14,300 kg in 240 days. These capabilities can be considerably increased by using separate Shuttle launches to bring up propellant and cargo, or by changing to mercury propellant.

Jaffe, L.; Beatty, R.; Bhandari, P.; Chow, E.; Deininger, W.; Ewell, R.; Fujita, T.; Grossman, M.; Kia, T.; Nesmith, B.

1987-01-01

59

Orbit Determination Accuracy for Comets on Earth-Impacting Trajectories  

NASA Technical Reports Server (NTRS)

The results presented show the level of orbit determination accuracy obtainable for long-period comets discovered approximately one year before collision with Earth. Preliminary orbits are determined from simulated observations using Gauss' method. Additional measurements are incorporated to improve the solution through the use of a Kalman filter, and include non-gravitational perturbations due to outgassing. Comparisons between observatories in several different circular heliocentric orbits show that observatories in orbits with radii less than 1 AU result in increased orbit determination accuracy for short tracking durations due to increased parallax per unit time. However, an observatory at 1 AU will perform similarly if the tracking duration is increased, and accuracy is significantly improved if additional observatories are positioned at the Sun-Earth Lagrange points L3, L4, or L5. A single observatory at 1 AU capable of both optical and range measurements yields the highest orbit determination accuracy in the shortest amount of time when compared to other systems of observatories.

Kay-Bunnell, Linda

2004-01-01

60

Preliminary Optimal Orbit Design for the Laser Interferometer Space Antenna (LISA)  

NASA Technical Reports Server (NTRS)

In this paper we present a preliminary optimal orbit analysis for the Laser Interferometer Space Antenna (LISA). LISA is a NASA/ESA mission to study gravitational waves and test predictions of general relativity. The nominal formation consists of three spacecraft in heliocentric orbits at 1 AU and trailing the Earth by twenty degrees. This configuration was chosen as a trade off to reduce the noise sources that will affect the instrument and to reduce the fuel to achieve the final orbit. We present equations for the nominal orbit design and discuss several different measures of performance for the LISA formation. All of the measures directly relate the formation dynamics to science performance. Also, constraints on the formation dynamics due to spacecraft and instrument limitations are discussed. Using the nominal solution as an initial guess, the formation is optimized using Sequential Quadratic Programming to maximize the performance while satisfying a set of nonlinear constraints. Results are presented for each of the performance measures.

Hughes, Steven P.; Bauer, Frank H. (Technical Monitor)

2002-01-01

61

Achieving Orbit  

NSDL National Science Digital Library

In this Engineering Design Challenge activity, learners will use balloons to investigate how a multi-stage rocket, like that used in the Interstellar Boundary Explorer (IBEX) mission, can propel a satellite to a specific orbit. Participants will construct a two-stage balloon rocket that will be required to reach a particular location on the balloon track, simulating the proper orbit to be reached by the IBEX satellite. If you need an audio version of this material, the file is compatible with screen reading software such as Adobe Acrobat Reader.

2012-07-17

62

Orbital Elements  

NSDL National Science Digital Library

Coordinates for tracking the International Space Station and the Mir Space Station are available here from NASA's Johnson Space Center Flight Design and Dynamics Division. The Orbital Elements page offers real-time data for use in ground track plotting programs. The site cautions the data are for ground track plotting programs only and "should not be used for precise applications or analysis!"

63

Elliptical Orbits  

NSDL National Science Digital Library

Although not inquiry, this activity is important for students to understand what an ellipse is and what a focus is, and to break misconceptions about Earth's orbit being highly elliptical. This is the perfect place to check to see if students have the mis

Horton, Michael

2009-05-30

64

Orbital Effects on Mercury's Escaping Sodium Exosphere  

NASA Technical Reports Server (NTRS)

We present results from coronagraphic imaging of Mercury's sodium tail over a 7 deg field of view. Several sets of observations made at the McDonald Observatory since May 2007 show a tail of neutral sodium atoms stretching more than 1000 Mercury radii (R(sub m)) in length, or a full degree of sky. However, no tail was observed extending beyond 120 R(sub m) during the January 2008 MESSENGER Fly-by period, or during a similar orbital phase of Mercury in July 2008. Large changes in Mercury's heliocentric radial velocity cause Doppler shifts about the Fraunhofer absorption features; the resultant change in solar flux and radiation pressure is the primary cause of the observed variation in tail brightness. Smaller fluctuations in brightness may exist due to changing source rates at the surface, but we have no explicit evidence for such changes in this data set. The effects of radiation pressure on Mercury's escaping atmosphere are investigated using seven observations spanning different orbital phases. Total escape rates of atmospheric sodium are estimated to be between 5 and 13 x 10(exp 23) atoms/s and show a correlation to radiation pressure. Candidate sources of Mercury's sodium exosphere include desorption by UV sunlight, thermal desorption, solar wind channeled along Mercury's magnetic field lines, and micro-meteor impacts. Wide-angle observations of the full extent of Mercury's sodium tail offer opportunities to enhance our understanding of the time histories of these source rates.

Schmidt, Carl A.; Wilson, Jody K.; Baumgardner, Jeffrey; Mendillo, Michael

2009-01-01

65

Orbiting Hotel  

NSDL National Science Digital Library

It is the year 2025 and a large company, Z-Tech, wants to put a hotel in space having it orbit around one of the planets in our solar system. Our 9th grade class has been given a very important job. We have to search for the perfect location for the hotel. Our job is to report back to the company with the planet that is the best place for an orbiting hotel. The Task: You are to write a report recommending which planet should be chosen. Your report should include pictures of the planet you recommended. Here are the questions you should answer in order to report back to Z-Tech with your recommendation. * Which planet will be the ...

Hicken, Mrs.

2009-10-19

66

Correlation of Kuiper Belt Object Colors With Orbital Properties: Gray Objects In Hot Orbits  

NASA Astrophysics Data System (ADS)

In our continuing BVR photometric survey of Kuiper belt objects (KBOs), we find that certain dynamical classes of KBOs exhibit very distinctive surface colors. In our data, 17 of 20 objects on large-inclination and large-eccentricity orbits with aphelion distances larger than 70 AU (a dynamically hot population) exhibit gray, B-R < 1.5, surface colors. In contrast, 21 of 21 classical KBOs on small-inclination and small-eccentricity orbits with perihelion distances larger than 40 AU (a dynamically cold population) exhibit red surface colors, B-R > 1.5. Finally, we find 22 Centaurs divide into two very different color populations, gray and red. These observations are consistent with a primordial origin of KBO surface colors based on their original heliocentric distance. Gray objects may have formed closer to the Sun in regions subject to orbital perturbations by an outward migrating Neptune, resulting in hot orbits. Red objects formed farther from the Sun and would be only partly perturbed by Neptune (contributing to the Centaur population). The furthest objects (red surfaces, cooler orbits) would remain unperturbed. Our observations were taken using CCD cameras on the Keck I 10-m telescope on Mauna Kea, Hawaii, the University of Arizona 2.3-m telescope on Kitt Peak, Arizona, and the Vatican Advanced Technology 1.8-m Telescope on Mt. Graham, Arizona. We thank the NASA Planetary Astronomy Program for support of our work (NAG5-12694) and the NASA Keck, Steward Observatory, and Vatican Observatory Time Allocation Committees for consistent allocation of telescope time.

Tegler, S. C.; Romanishin, W.; Consolmagno, G.

2003-05-01

67

Theory of satellite orbit-orbit resonance  

Microsoft Academic Search

On the basis of the strong mathematical and physical parallels between orbit-orbit and spin-orbit resonances, the dynamics of mutual orbit perturbations between two satellites about a massive planet are examined, exploiting an approach previously adopted in the study of spin-orbit coupling. The satellites are assumed to have arbitrary mass ratio and to move in non-intersecting orbits of arbitrary size and

Leon Blitzer; John D. Anderson

1981-01-01

68

Orbit analysis  

SciTech Connect

The past fifteen years have witnessed a remarkable development of methods for analyzing single particle orbit dynamics in accelerators. Unlike their more classic counterparts, which act upon differential equations, these methods proceed by manipulating Poincare maps directly. This attribute makes them well matched for studying accelerators whose physics is most naturally modelled in terms of maps, an observation that has been championed most vigorously by Forest. In the following sections the author sketchs a little background, explains some of the physics underlying these techniques, and discusses the best computing strategy for implementing them in conjunction with modeling accelerators.

Michelotti, L.

1995-01-01

69

Shapes of d Orbitals  

NSDL National Science Digital Library

Shapes of d Orbitals shows the d orbitals in an axis set. Running the mouse over an orbital reveals the "name" of that orbital. This is good practice for helping students link the name of an orbital to the orientation.Shapes of d Orbitals has a link to D Orbitals in an Octahedral Ligand Field. Here the user may click on the name of any one of the d orbitals to obtain a larger 3-dimensional image. The images are rotatable and scalable. Orbital phase is shown by the different colors.

70

Orbiter/launch system  

NASA Technical Reports Server (NTRS)

The system includes reusable turbojet propelled booster vehicles releasably connected to a reusable rocket powered orbit vehicle. The coupled orbiter-booster combination takes off horizontally and ascends to staging altitude and speed under booster power with both orbiter and booster wings providing lift. After staging, the booster vehicles fly back to Earth for horizontal landing and the orbiter vehicle continues ascending to orbit.

Jackson, L. R.; Weidner, J. P.; Small, W. J.; Martin, J. A. (inventors)

1981-01-01

71

Orbit design concepts for Jupiter orbiter missions  

NASA Technical Reports Server (NTRS)

Advanced mission and orbit planning efforts are currently in progress for a Mariner-class Jupiter orbiter. Baseline spacecraft and orbit design criteria are the goals of a NASA effort to define such a mission. Orbit design concepts that have been discovered during the early stages of mission planning are both challenging and exciting. A description is given of several such concepts that may greatly increase the flexibility and scientific return of orbiters designed for close study of the Galilean satellites and exploration of the Jovian system. Some new jargon is introduced in discussions to describe the exploitation of gravity-assist trajectories using the giant satellites for orbit control. Orbit 'pumping' and 'cranking' and 'resonance hopping' are defined and shown to be dynamically feasible means of controlling the orbit and, thus, the scientific return. A candidate encounter sequence is presented for an equatorial tour of the Galilean moons.

Uphoff, C.; Roberts, P. H.; Friedman, L. D.

1974-01-01

72

Working With Orbits  

NSDL National Science Digital Library

This site offers two programs to illustrate how orbits work. The Orbital Elements calculator contains animations to see how the appearance of an orbit depends on the values of the orbital elements which include distance from the Sun, eccentricity, pericenter location and anomaly. This is available in two or three dimensions. The Solar System allows users to watch several planets in our Solar System simultaneously orbit the Sun. An additional object (asteroid or comet) is present and users change the orbital parameters to see what types of orbits are possible for this object.

Douglas Hamilton

73

Orbital fractures: a review  

PubMed Central

This review of orbital fractures has three goals: 1) to understand the clinically relevant orbital anatomy with regard to periorbital trauma and orbital fractures, 2) to explain how to assess and examine a patient after periorbital trauma, and 3) to understand the medical and surgical management of orbital fractures. The article aims to summarize the evaluation and management of commonly encountered orbital fractures from the ophthalmologic perspective and to provide an overview for all practicing ophthalmologists and ophthalmologists in training. PMID:21339801

Joseph, Jeffrey M; Glavas, Ioannis P

2011-01-01

74

Theory of satellite orbit-orbit resonance  

NASA Technical Reports Server (NTRS)

On the basis of the strong mathematical and physical parallels between orbit-orbit and spin-orbit resonances, the dynamics of mutual orbit perturbations between two satellites about a massive planet are examined, exploiting an approach previously adopted in the study of spin-orbit coupling. Resonances are found to exist when the mean orbital periods are commensurable with respect to some rotating axis, which condition also involves the apsidal and nodal motions of both satellites. In any resonant state the satellites are effectively trapped in separate potential wells, and a single variable is found to describe the simultaneous librations of both satellites. The librations in longitude are 180 deg out-of-phase, with fixed amplitude ratio that depends only on their relative masses and semimajor axes. The theory is applicable to Saturn's resonant pairs Titan-Hyperion and Mimas-Tethys, and in these cases the calculated libration periods are in reasonably good agreement with the observed periods.

Blitzer, L.; Anderson, J. D.

1981-01-01

75

Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis  

NASA Technical Reports Server (NTRS)

Results from operational OD produced by the NASA Goddard Flight Dynamics Facility for the LRO nominal and extended mission are presented. During the LRO nominal mission, when LRO flew in a low circular orbit, orbit determination requirements were met nearly 100% of the time. When the extended mission began, LRO returned to a more elliptical frozen orbit where gravity and other modeling errors caused numerous violations of mission accuracy requirements. Prediction accuracy is particularly challenged during periods when LRO is in full-Sun. A series of improvements to LRO orbit determination are presented, including implementation of new lunar gravity models, improved spacecraft solar radiation pressure modeling using a dynamic multi-plate area model, a shorter orbit determination arc length, and a constrained plane method for estimation. The analysis presented in this paper shows that updated lunar gravity models improved accuracy in the frozen orbit, and a multiplate dynamic area model improves prediction accuracy during full-Sun orbit periods. Implementation of a 36-hour tracking data arc and plane constraints during edge-on orbit geometry also provide benefits. A comparison of the operational solutions to precision orbit determination solutions shows agreement on a 100- to 250-meter level in definitive accuracy.

Slojkowski, Steven E.

2014-01-01

76

Manned Venus Orbiting Mission  

NASA Technical Reports Server (NTRS)

Manned orbiting stopover round trips to Venus are studied for departure dates between 1975 and 1986 over a range of trip times and stay times. The use of highly elliptic parking orbits at Venus leads to low initial weights in Earth orbit compared with circular orbits. For the elliptic parking orbit, the effect of constraints on the low altitude observation time on the initial weight is shown. The mission can be accomplished with the Apollo level of chemical propulsion, but advanced chemical or nuclear propulsion can give large weight reductions. The Venus orbiting mission weights than the corresponding Mars mission.

Willis, E. A., Jr.

1967-01-01

77

Lunar orbiting prospector  

NASA Technical Reports Server (NTRS)

One of the prime reasons for establishing a manned lunar presence is the possibility of using the potential lunar resources. The Lunar Orbital Prospector (LOP) is a lunar orbiting platform whose mission is to prospect and explore the Moon from orbit in support of early lunar colonization and exploitation efforts. The LOP mission is divided into three primary phases: transport from Earth to low lunar orbit (LLO), operation in lunar orbit, and platform servicing in lunar orbit. The platform alters its orbit to obtain the desired surface viewing, and the orbit can be changed periodically as needed. After completion of the inital remote sensing mission, more ambitious and/or complicated prospecting and exploration missions can be contemplated. A refueled propulsion module, updated instruments, or additional remote sensing packages can be flown up from the lunar base to the platform.

1988-01-01

78

Orbiting Binary Stars  

NSDL National Science Digital Library

This simulation demonstrates the path of binary stars' orbit. The user is able to set the masses, orbital separation, orbital eccentricity, the inclination angle to our line of sight, and the angle of the nodes of two orbiting stars. The observed velocities of the two stars, and the Doppler shifted spectral lines are also shown in the upper right box. The site also includes definitions of terms used, instructions on how to use the simulation and a few examples.

Kolena, John

2007-12-11

79

Hydatid cyst of orbit.  

PubMed

A 40-year-old woman presented with protrusion and diminution of vision of left eye for 3 months. CT scan of orbit revealed an intra-orbital cystic space occupying lesion. Exenteration of the left orbit was done and histopathological examination of the cystic mass proved it to be a case of hydatid cyst. PMID:22480108

Bhaduri, Gautam; Chatterjee, Soumya Swarup; Gayen, Sharmistha; Goswami, Soumik

2011-09-01

80

Five Equivalent d Orbitals  

ERIC Educational Resources Information Center

Amplifies and clarifies a previous paper on pyramidal d orbitals. Discusses two sets of pyramid d orbitals with respect to their maximum bond strength and their symmetry. Authors described the oblate and prolate pentagonal antiprisms arising from the two sets of five equivalent d orbitals. (RR)

Pauling, Linus; McClure, Vance

1970-01-01

81

Mars Reconnaissance Orbiter  

NSDL National Science Digital Library

This is the mission web site for the Mars Reconnaissance Orbiter, which went into orbit around Mars on March 10, 2006. The site provides links to updates and information about the project. The site features links to Mars Reconnaissance Orbiter images, animations, and datasets. Science operations commence in November, 2006.

Laboratory, Jet P.; Administration, National A.

82

SEASAT B orbit synthesis  

NASA Technical Reports Server (NTRS)

Addition were made to Battelle's Interactive Graphics Orbit Selection (IGOS) program; IGOS was exercised via telephone lines from JPL, and candidate SEASAT orbits were analyzed by Battelle. The additions to the program enable clear understanding of the implications of a specific orbit to the diverse desires of the SEASAT user community.

Rea, F. G.; Warmke, J. M.

1976-01-01

83

Bound central orbits  

NASA Astrophysics Data System (ADS)

The orbits in any central potential are described analytically and new expressions are derived for their periods and precession rates. A simple perturbation theory allows their delineation to any accuracy. Kepler's equation is generalized to such orbits and angle and action variables are given for them. A new property of orbits under inverse fifth power forces is found.

Lynden-Bell, D.

2015-02-01

84

Orbits in Space  

NSDL National Science Digital Library

This discussion of orbits around the Earth and Sun begins by describing synchronous orbits and then explains how satellites in low orbits encounter atmospheric interference. There is an explanation of how the bulge of the Earth affects the calculation of an Earth orbit. The satellites stationed at the Lagrangian Point L1, ACE and SOHO are discussed along with information on the other Lagrangian points. Finally, there is information about other orbits within our solar system and an explanation of why it is no easy task to get to the Sun.

David Stern

85

Orbital Evolution of Asteroids  

NASA Astrophysics Data System (ADS)

The synthetic orbital frequencies and eccentricities of main belt asteroids computed by Knezevic and Milani [2] show evidence that the structure of the asteroid belt has been determined by a dense of web of high-order resonances. By examining the orbital frequency distribution at high resolution, we discover a correlation between asteroid number density, mean orbital eccentricity and Lyapunov Characteristic Exponent. In particular, the orbital eccentricities of asteroids trapped in resonance tend to be higher than those of non-resonant asteroids and we argue that this is observational evidence for orbital evolution due to chaotic diffusion.

Dermott, S. F.; Kehoe, T. J. J.

2011-10-01

86

Orbit Software Suite  

NASA Technical Reports Server (NTRS)

Orbit Software Suite is used to support a variety of NASA/DM (Dependable Multiprocessor) mission planning and analysis activities on the IPS (Intrusion Prevention System) platform. The suite of Orbit software tools (Orbit Design and Orbit Dynamics) resides on IPS/Linux workstations, and is used to perform mission design and analysis tasks corresponding to trajectory/ launch window, rendezvous, and proximity operations flight segments. A list of tools in Orbit Software Suite represents tool versions established during/after the Equipment Rehost-3 Project.

Osgood, Cathy; Williams, Kevin; Gentry, Philip; Brownfield, Dana; Hallstrom, John; Stuit, Tim

2012-01-01

87

Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis  

NASA Technical Reports Server (NTRS)

LRO definitive and predictive accuracy requirements were easily met in the nominal mission orbit, using the LP150Q lunar gravity model. center dot Accuracy of the LP150Q model is poorer in the extended mission elliptical orbit. center dot Later lunar gravity models, in particular GSFC-GRAIL-270, improve OD accuracy in the extended mission. center dot Implementation of a constrained plane when the orbit is within 45 degrees of the Earth-Moon line improves cross-track accuracy. center dot Prediction accuracy is still challenged during full-Sun periods due to coarse spacecraft area modeling - Implementation of a multi-plate area model with definitive attitude input can eliminate prediction violations. - The FDF is evaluating using analytic and predicted attitude modeling to improve full-Sun prediction accuracy. center dot Comparison of FDF ephemeris file to high-precision ephemeris files provides gross confirmation that overlap compares properly assess orbit accuracy.

Slojkowski, Steven E.

2014-01-01

88

Transneptunian orbit computation Jenni Virtanen  

E-print Network

Transneptunian orbit computation Jenni Virtanen Finnish Geodetic Institute Gonzalo Tancredi Observatory Karri Muinonen University of Helsinki We review the orbit computation problem orbital arcs, which are known to be coupled with large uncertainties in orbital elements. Currently

Bernstein, Gary

89

Orbit Determination of the Lunar Reconnaissance Orbiter  

NASA Technical Reports Server (NTRS)

We present the results on precision orbit determination from the radio science investigation of the Lunar Reconnaissance Orbiter (LRO) spacecraft. We describe the data, modeling and methods used to achieve position knowledge several times better than the required 50-100m (in total position), over the period from 13 July 2009 to 31 January 2011. In addition to the near-continuous radiometric tracking data, we include altimetric data from the Lunar Orbiter Laser Altimeter (LOLA) in the form of crossover measurements, and show that they strongly improve the accuracy of the orbit reconstruction (total position overlap differences decrease from approx.70m to approx.23 m). To refine the spacecraft trajectory further, we develop a lunar gravity field by combining the newly acquired LRO data with the historical data. The reprocessing of the spacecraft trajectory with that model shows significantly increased accuracy (approx.20m with only the radiometric data, and approx.14m with the addition of the altimetric crossovers). LOLA topographic maps and calibration data from the Lunar Reconnaissance Orbiter Camera were used to supplement the results of the overlap analysis and demonstrate the trajectory accuracy.

Mazarico, Erwan; Rowlands, D. D.; Neumann, G. A.; Smith, D. E.; Torrence, M. H.; Lemoine, F. G.; Zuber, M. T.

2011-01-01

90

Satellite orbit determination  

NASA Technical Reports Server (NTRS)

A historic account of the activities of the Satellite OD Group during the MM'71 mission is given along with an assessment of the accuracy of the determined orbit of the Mariner 9 spacecraft. Preflight study results are reviewed, and the major error sources described. Tracking and data fitting strategy actually used in the real time operations is itemized, and Deep Space Network data available for orbit fitting during the mission and the auxiliary information used by the navigation team are described. A detailed orbit fitting history of the first four revolutions of the satellite orbit of Mariner 9 is presented, with emphasis on the convergence problems and the delivered solution for the first orbit trim maneuver. Also included are a solution accuracy summary, the history of the spacecraft orbit osculating elements, the results of verifying the radio solutions with TV imaging data, and a summary of the normal points generated for the relativity experiment.

Jordan, J. F.; Boggs, D. H.; Born, G. H.; Christensen, E. J.; Ferrari, A. J.; Green, D. W.; Hylkema, R. K.; Mohan, S. N.; Reinbold, S. J.; Sievers, G. L.

1973-01-01

91

Orbital myositis complicating sinusitis  

PubMed Central

Orbital myositis is a common cause of extraocular muscle enlargement. It is characterized by nonspecific inflammation of one or more extraocular muscles. Although often idiopathic in origin, orbital myositis has been associated with various noninfectious diseases. Several cases have also been reported as occurring after upper respiratory tract infections. The present report describes a case of orbital myositis together with subclinical sinusitis and its rapid resolution after antibiotic treatment. The literature on this clinical entity is also reviewed. PMID:18159317

Dylewski, Joe S; Drummond, Robert; Townsend, Tiffany

2001-01-01

92

Family of Orbiters  

NASA Technical Reports Server (NTRS)

This image shows the paths of three spacecraft currently in orbit around Mars, as well as the path by which NASA's Phoenix Mars Lander will approach and land on the planet. The t-shaped crosses show where the orbiters will be when Phoenix enters the atmosphere, while the x-shaped crosses show their location at landing time.

All three orbiters, NASA's Mars Reconnaissance Orbiter, NASA's Mars Odyssey and the European Space Agency's Mars Express, will be monitoring Phoenix during the final steps of its journey to the Red Planet.

Phoenix will land just south of Mars's north polar ice cap.

2008-01-01

93

Titan Orbiter Aerorover Mission  

NASA Technical Reports Server (NTRS)

We propose a combined Titan orbiter and Titan Aerorover mission with an emphasis on both in situ and remote sensing measurements of Titan's surface, atmosphere, ionosphere, and magnetospheric interaction. The biological aspect of the Titan environment will be emphasized by the mission (i.e., search for organic materials which may include simple organics to 'amono' analogues of amino acids and possibly more complex, lightening detection and infrared, ultraviolet, and charged particle interactions with Titan's surface and atmosphere). An international mission is assumed to control costs. NASA will provide the orbiter, launch vehicle, DSN coverage and operations, while international partners will provide the Aerorover and up to 30% of the cost for the scientific instruments through collaborative efforts. To further reduce costs we propose a single PI for orbiter science instruments and a single PI for Aerorover science instruments. This approach will provide single command/data and power interface between spacecraft and orbiter instruments that will have redundant central DPU and power converter for their instruments. A similar approach could be used for the Aerorover. The mission profile will be constructed to minimize conflicts between Aerorover science, orbiter radar science, orbiter radio science, orbiter imaging science, and orbiter fields and particles (FP) science. Additional information is contained in the original extended abstract.

Sittler Jr., E. C.; Acuna, M.; Burchell, M. J.; Coates, A.; Farrell, W.; Flasar, M.; Goldstein, B. E.; Gorevan, S.; Hartle, R. E.; Johnson, W. T. K.

2001-01-01

94

Orbital trapdoor fractures  

PubMed Central

Orbital trapdoor fractures are commonly encountered in children. Awareness of trapdoor fractures is of particular importance. This is because early recognition and treatment are necessary to prevent permanent motility abnormities. In this article, we will provide a brief overview of orbital fractures. The clinical and radiographic features of trapdoor fractures will then be reviewed, followed by a discussion on their proper management. PMID:23961006

Phan, Laura T.; Jordan Piluek, W.; McCulley, Timothy J.

2012-01-01

95

Orbits R Us!  

NSDL National Science Digital Library

This site introduces the principle of geosynchronous orbits and geostationary weather satellites in non-technical terms. Several animations show how they work. The GOES (Geostationary Operational Environmental Satellite) and POES (Polar-orbiting Operational Environmental Satellites) satellite programs at NASA and NOAA are briefly explained.

96

Idiopathic orbital myositis mimicking orbital cellulitis.  

PubMed

Idiopathic orbital myositis (IOM) is a subtype of orbital inflammatory disease characterized by primarily involving the extraocular muscle. The signs and symptoms of IOM may also be seen in such processes as orbital cellulitis, primary or metastatic orbital neoplasm, carotid-cavernous fistulae, arteriovenous malformations, cavernous sinus thrombosis, and thyroid eye disease, and because there is no pathognomonic sign, symptoms, laboratory test, or radiologic findings, its diagnosis is often provisional. In our case, diagnosis of IOM was more difficult because our patient presented with proptosis after alloplastic implant insertion in the blow-out fracture. After considering radiologic and physical findings, we concluded that cellulitis was more likely as initial diagnosis. To remove foreign body or pus, surgical exploration was done, but intraoperative findings did not show any pus or sign of infection but diffuse enlargement and swelling of inferior rectus muscle. The diagnosis was confirmed as IOM, and the patient was treated with systemic corticosteroid. Although proptosis after alloplastic insertion in blow-out fracture is usually a sign of cellulitis, this case illustrates that it may also occur in patients with IOM. PMID:20485087

Kim, Dong Seok; Lee, Jung Ho; Oh, Deuk Young; Seo, Je Won; Ahn, Sang Tae; Rhie, Jong Won

2010-05-01

97

Moon Lunar Orbiter - Lunar Orbiter III  

NASA Technical Reports Server (NTRS)

The hidden or dark side of the Moon was taken by Lunar Orbiter III During its mission to photograph potential lunar-landing sites for Apollo missions. Photograph published in Winds of Change, 75th Anniversary NASA publication (page 94), by James Schultz.

1967-01-01

98

Mars Climate Orbiter  

NASA Technical Reports Server (NTRS)

The purpose of this mission is to study the climate history and the water distribution of Mars. Beautiful panoramic views of the shuttle on the launch pad, engine ignition, Rocket launch, and the separation and burnout of the Solid Rocket Boosters are shown. The footage also includes an animation of the mission. Detailed views of the path that the Orbiter traversed were shown. Once the Orbiter lands on the surface of Mars, it will dig a six to eight inch hole and collect samples from the planets' surface. The animation also included the prospective return of the Orbiter to Earth over the desert of Utah. The remote sensor on the Orbiter helps in finding the exact location of the Orbiter so that scientists may collect the sample and analyze it.

1998-01-01

99

Remote Controlled Orbiter Capability  

NASA Technical Reports Server (NTRS)

The Remote Control Orbiter (RCO) capability allows a Space Shuttle Orbiter to perform an unmanned re-entry and landing. This low-cost capability employs existing and newly added functions to perform key activities typically performed by flight crews and controllers during manned re-entries. During an RCO landing attempt, these functions are triggered by automation resident in the on-board computers or uplinked commands from flight controllers on the ground. In order to properly route certain commands to the appropriate hardware, an In-Flight Maintenance (IFM) cable was developed. Currently, the RCO capability is reserved for the scenario where a safe return of the crew from orbit may not be possible. The flight crew would remain in orbit and await a rescue mission. After the crew is rescued, the RCO capability would be used on the unmanned Orbiter in an attempt to salvage this national asset.

Garske, Michael; delaTorre, Rafael

2007-01-01

100

Orbital Debris Mitigation  

NASA Technical Reports Server (NTRS)

Policies on limiting orbital debris are found throughout the US Government, many foreign space agencies, and as adopted guidelines in the United Nations. The underlying purpose of these policies is to ensure the environment remains safe for the operation of robotic and human spacecraft in near- Earth orbit. For this reason, it is important to consider orbital debris mitigation during the design of all space vehicles. Documenting compliance with the debris mitigation guidelines occurs after the vehicle has already been designed and fabricated for many CubeSats, whereas larger satellites are evaluated throughout the design process. This paper will provide a brief explanation of the US Government Orbital Debris Mitigation Standard Practices, a discussion of international guidelines, as well as NASA's process for compliance evaluation. In addition, it will discuss the educational value of considering orbital debris mitigation requirements as a part of student built satellite design.

Kelley, R. L.; Jarkey, D. R.; Stansbery, G.

2014-01-01

101

Visualization of atom's orbits.  

PubMed

High-resolution imaging techniques have been used to obtain views of internal shapes of single atoms or columns of atoms. This review article focuses on the visualization of internal atomic structures such as the configurations of electron orbits confined to atoms. This is accomplished by applying visualization techniques to the reported images of atoms or molecules as well as static and dynamic ions in a plasma. It was found that the photon and electron energies provide macroscopic and microscopic views of the orbit structures of atoms, respectively. The laser-imaged atoms showed a rugged orbit structure, containing alternating dark and bright orbits believed to be the pathways for an externally supplied laser energy and internally excited electron energy, respectively. By contrast, the atoms taken by the electron microscopy provided a structure of fine electron orbits, systematically formed in increasing order of grayscale representing the energy state of an orbit. This structure was identical to those of the plasma ions. The visualized electronic structures played a critical role in clarifying vague postulates made in the Bohr model. Main features proposed in the atomic model are the dynamic orbits absorbing an externally supplied electromagnetic energy, electron emission from them while accompanying light radiation, and frequency of electron waves not light. The light-accompanying electrons and ionic speckles induced by laser light signify that light is composed of electrons and ions. PMID:24749452

Kim, Byungwhan

2014-02-01

102

External Resource: What is orbit?  

NSDL National Science Digital Library

A 5-8 NASA Education reference answering the question, " What is orbit?" Topics include: satellite, ecliptic plane, perigee, apogee, escape velocity, geosynchronous, polar orbits, and low Earth orbit.

1900-01-01

103

Removal of orbital debris  

NASA Technical Reports Server (NTRS)

The several methods presently identified for the reduction of orbital debris populations are broadly classifiable as either preventive or remedial, and fall within distinctive operational regimes. For all particles, (1) in the 250-2000-km altitude band, intelligent sweepers may be used; (2) for large objects, in the 80-250-km altitude band, orbital decay renders removal impractical; (3) for the 250-750-km altitude band, deorbit devices should be used; (4) for 750-2500-km altitude, OMV rendezvous for propulsive deorbit package attachment is foreseeable; and beyond 2500 km, (5) propulsive escape from earth orbit is required.

Petro, Andrew J.; Talent, David L.

1989-01-01

104

Space Shuttle Orbiter  

NSDL National Science Digital Library

Students learn how orbits are created by a force pulling toward the center in this Moveable Museum unit, in which they build a paper model of a Space Shuttle. This activity simulates an object in orbit. A paper Space Shuttle is swung in a circle on a string. The string provides a pull toward the center of the orbit, simulating the force of gravity. The four-page PDF guide includes suggested background readings for educators, activity notes, and step-by-step directions with suggested discussion questions for older students.

105

The Tajikistan superbolide of July 23, 2008. I. Trajectory, orbit, and preliminary fall data  

NASA Astrophysics Data System (ADS)

The results of the atmospheric trajectory, radiant, heliocentric orbit, and preliminary strewn field calculations for an extremely bright slow-moving fireball are presented. In the evening hours of July 23, 2008, a bright object entered Earth's atmosphere over Tajikistan. The fireball had a -20.3 maximum absolute magnitude and a spectacularly long persistent dust trail remained visible over a widespread region of Tajikistan for about 28 minutes after sunset. The fireball was also recorded by a visible-light satellite system at 14 h 45 min 25 s UT, and the dust trail was imaged by video and photocameras. A unique aspect of this event is that it was detected by two infrasound and five seismic stations too. The bolide was first recorded at a height of 38.2 km, reached its maximum brightness at a height of 35.0 km, and finished at a height of 19.6 km. The first breakup occurred under an aerodynamic pressure of approximately 1.6 MPa, similar to the values derived for breakups of the scarcely reported meteorite-dropping bolides. The fireball's trajectory and dynamic results suggest that meteorite survival is likely. The meteoroid followed an Apollo-like asteroid orbit comparable to those derived for previously recovered meteorites with accurately known orbits.

Konovalova, Natalia A.; Madiedo, Jose M.; Trigo-Rodríguez, Josep M.

2013-12-01

106

Orbit Determination Issues for Libration Point Orbits  

NASA Technical Reports Server (NTRS)

Libration point mission designers require knowledge of orbital accuracy for a variety of analyses including station keeping control strategies, transfer trajectory design, and formation and constellation control. Past publications have detailed orbit determination (OD) results from individual libration point missions. This paper collects both published and unpublished results from four previous libration point missions (ISEE (International Sun-Earth Explorer) -3, SOHO (Solar and Heliospheric Observatory), ACE (Advanced Composition Explorer) and MAP (Microwave Anisotropy Probe)) supported by Goddard Space Flight Center's Guidance, Navigation & Control Center. The results of those missions are presented along with OD issues specific to each mission. All past missions have been limited to ground based tracking through NASA ground sites using standard range and Doppler measurement types. Advanced technology is enabling other OD options including onboard navigation using seaboard attitude sensors and the use of the Very Long Baseline Interferometry (VLBI) measurement Delta Differenced One-Way Range (DDOR). Both options potentially enable missions to reduce coherent dedicated tracking passes while maintaining orbital accuracy. With the increased projected loading of the DSN (Deep Space Network), missions must find alternatives to the standard OD scenario.

Beckman, Mark; Bauer, Frank (Technical Monitor)

2002-01-01

107

Orbit Determination Issues for Libration Point Orbits  

NASA Technical Reports Server (NTRS)

Libration point mission designers require knowledge of orbital accuracy for a variety of analyses including station keeping control strategies, transfer trajectory design, and formation and constellation control. Past publications have detailed orbit determination (OD) results from individual notation point missions. This paper collects both published and unpublished results from four previous notation point missions (ISEE-3, SOHO, ACE and MAP) supported by Goddard Space Flight Center's Guidance, Navigation & Control Center. The results of those missions are presented along with OD issues specific to each mission. All past missions have been limited to ground based tracking through NASA ground sites using standard marine and Doppler measurement types. Advanced technology is enabling other OD options including onboard navigation using onboard attitude sensors and the use of the Very Long Baseline Interferometry (VLBI) measurement Delta Differenced One-Way Range (DDOR). Both options potentially enable missions to reduce coherent dedicated tracking passes while maintaining orbital accuracy. With the increased projected loading of the DSN, missions must find alternatives to the standard OD scenario.

Beckman, Mark; Bauer, Frank (Technical Monitor)

2002-01-01

108

Altimetry, Orbits and Tides  

NASA Technical Reports Server (NTRS)

The nature of the orbit error and its effect on the sea surface heights calculated with satellite altimetry are explained. The elementary concepts of celestial mechanics required to follow a general discussion of the problem are included. Consideration of errors in the orbits of satellites with precisely repeating ground tracks (SEASAT, TOPEX, ERS-1, POSEIDON, amongst past and future altimeter satellites) are detailed. The theoretical conclusions are illustrated with the numerical results of computer simulations. The nature of the errors in this type of orbits is such that this error can be filtered out by using height differences along repeating (overlapping) passes. This makes them particularly valuable for the study and monitoring of changes in the sea surface, such as tides. Elements of tidal theory, showing how these principles can be combined with those pertinent to the orbit error to make direct maps of the tides using altimetry are presented.

Colombo, O. L.

1984-01-01

109

Habitability study shuttle orbiter  

NASA Technical Reports Server (NTRS)

Habitability design concepts for the Shuttle Orbiter Program are provided for MSC. A variety of creative solutions for the stated tasks are presented. Sketches, mock-ups, mechanicals and models are included for establishing a foundation for future development.

1973-01-01

110

Imaging in orbital trauma  

PubMed Central

Orbital trauma is one of the most common reasons for ophthalmology specialty consultation in the emergency department setting. We survey the literature from 1990 to present to describe the role of computed tomography (CT), magnetic resonance imaging (MRI) and their associated angiography in some of the most commonly encountered orbital trauma conditions. CT orbit can often detect certain types of foreign bodies, lens dislocation, ruptured globe, choroidal or retinal detachments, or cavernous sinus thrombosis and thus complement a bedside ophthalmic exam that can sometimes be limited in the setting of trauma. CT remains the workhorse for acute orbital trauma owing to its rapidity and ability to delineate bony abnormalities; however MRI remains an important modality in special circumstances such as soft tissue assessment or with organic foreign bodies. PMID:23961028

Lin, Ken Y.; Ngai, Philip; Echegoyen, Julio C.; Tao, Jeremiah P.

2012-01-01

111

Orbiter thermal protection system  

NASA Technical Reports Server (NTRS)

The major material and design challenges associated with the orbiter thermal protection system (TPS), the various TPS materials that are used, the different design approaches associated with each of the materials, and the performance during the flight test program are described. The first five flights of the Orbiter Columbia and the initial flight of the Orbiter Challenger provided the data necessary to verify the TPS thermal performance, structural integrity, and reusability. The flight performance characteristics of each TPS material are discussed, based on postflight inspections and postflight interpretation of the flight instrumentation data. Flights to date indicate that the thermal and structural design requirements for the orbiter TPS are met and that the overall performance is outstanding.

Dotts, R. L.; Curry, D. M.; Tillian, D. J.

1985-01-01

112

Orbit Physlet Problems  

NSDL National Science Digital Library

A Danish Website for Interactive Science Education. Html pages in this directory contain scripts that were written by Morten Brydensholt and coworkers for the Orbit website. This commercial website is in Danish. This site provides English translations of this material.

Wolfgang Christian

113

Optical orbital debris spotter  

NASA Astrophysics Data System (ADS)

The number of man-made debris objects orbiting the Earth, or orbital debris, is alarmingly increasing, resulting in the increased probability of degradation, damage, or destruction of operating spacecraft. In part, small objects (<10 cm) in Low Earth Orbit (LEO) are of concern because they are abundant and difficult to track or even to detect on a routine basis. Due to the increasing debris population it is reasonable to assume that improved capabilities for on-orbit damage attribution, in addition to increased capabilities to detect and track small objects are needed. Here we present a sensor concept to detect small debris with sizes between approximately 1.0 and 0.01 cm in the vicinity of a host spacecraft for near real time damage attribution and characterization of dense debris fields and potentially to provide additional data to existing debris models.

Englert, Christoph R.; Bays, J. Timothy; Marr, Kenneth D.; Brown, Charles M.; Nicholas, Andrew C.; Finne, Theodore T.

2014-11-01

114

Imaging in orbital trauma.  

PubMed

Orbital trauma is one of the most common reasons for ophthalmology specialty consultation in the emergency department setting. We survey the literature from 1990 to present to describe the role of computed tomography (CT), magnetic resonance imaging (MRI) and their associated angiography in some of the most commonly encountered orbital trauma conditions. CT orbit can often detect certain types of foreign bodies, lens dislocation, ruptured globe, choroidal or retinal detachments, or cavernous sinus thrombosis and thus complement a bedside ophthalmic exam that can sometimes be limited in the setting of trauma. CT remains the workhorse for acute orbital trauma owing to its rapidity and ability to delineate bony abnormalities; however MRI remains an important modality in special circumstances such as soft tissue assessment or with organic foreign bodies. PMID:23961028

Lin, Ken Y; Ngai, Philip; Echegoyen, Julio C; Tao, Jeremiah P

2012-10-01

115

Tethered orbital refueling study  

NASA Technical Reports Server (NTRS)

One of the major applications of the space station will be to act as a refueling depot for cryogenic-fueled space-based orbital transfer vehicles (OTV), Earth-storable fueled orbit maneuvering vehicles, and refurbishable satellite spacecraft using hydrazine. One alternative for fuel storage at the space station is a tethered orbital refueling facility (TORF), separated from the space station by a sufficient distance to induce a gravity gradient force that settles the stored fuels. The technical feasibility was examined with the primary focus on the refueling of LO2/LH2 orbital transfer vehicles. Also examined was the tethered facility on the space station. It was compared to a zero-gravity facility. A tethered refueling facility should be considered as a viable alternative to a zero-gravity facility if the zero-gravity fluid transfer technology, such as the propellant management device and no vent fill, proves to be difficult to develop with the required performance.

Fester, Dale A.; Rudolph, L. Kevin; Kiefel, Erlinda R.; Abbott, Peter W.; Grossrode, Pat

1986-01-01

116

Aerobraking orbital transfer vehicle  

NASA Technical Reports Server (NTRS)

An aerobraking orbital transfer vehicle which includes an aerobraking device which also serves as a heat shield in the shape of a raked-off elliptic or circular cone with a circular or elliptical base, and with an ellipsoid or other blunt shape nose. The aerobraking device is fitted with a toroid-like skirt and is integral with the support structure of the propulsion system and other systems of the space vehicle. The vehicle is intended to be transported in components to a space station in lower earth orbit where it is assembled for use as a transportation system from low earth orbit to geosynchronous earth orbit and return. Conventional guidance means are included for autonomous flight.

Scott, Carl D. (Inventor); Nagy, Kornel (Inventor); Roberts, Barney B. (Inventor); Ried, Robert C. (Inventor); Kroll, Kenneth R. (Inventor); Gamble, Joe (Inventor)

1989-01-01

117

Space: Orbiting the Earth  

NSDL National Science Digital Library

In this activity, students solve various problems related to John Glenn's first ride into space, and complete calculations involving velocity, distance and time. Then they calculate the height a satellite would need to be to keep to a geosynchronous orbit.

2010-01-01

118

Orbiter entry aerothermodynamics  

NASA Technical Reports Server (NTRS)

The challenge in the definition of the entry aerothermodynamic environment arising from the challenge of a reliable and reusable Orbiter is reviewed in light of the existing technology. Select problems pertinent to the orbiter development are discussed with reference to comprehensive treatments. These problems include boundary layer transition, leeward-side heating, shock/shock interaction scaling, tile gap heating, and nonequilibrium effects such as surface catalysis. Sample measurements obtained from test flights of the Orbiter are presented with comparison to preflight expectations. Numerical and wind tunnel simulations gave efficient information for defining the entry environment and an adequate level of preflight confidence. The high quality flight data provide an opportunity to refine the operational capability of the orbiter and serve as a benchmark both for the development of aerothermodynamic technology and for use in meeting future entry heating challenges.

Ried, R. C.

1985-01-01

119

Ulysses orbit determination  

NASA Astrophysics Data System (ADS)

The Ulysses mission ESA spacecraft with ESA and NASA experiments explores the polar regions of the sun by sending a spacecraft on a trajectory out of the ecliptic after a Jupiter flyby. After correcting for launch errors and refining the aimpoint, orbit determination results show the change and general improvement in the Jupiter arrival point. Orbit determination results are further discussed, and future plans are mentioned.

Gordon, H. J.; Luthey, J. L.; McElrath, T. P.; Menon, P. R.

1992-08-01

120

A tapestry of orbits  

SciTech Connect

In this book, the author describes how orbital research developed to yield a rich harvest of knowledge about the earth and its atmosphere. King-Hele relates a personal account of this research based on analysis of satellite orbits between 1957 and 1990 conducted from the Royal Aircraft Establishment in Farnborough England. The early research methods used before the launch of Sputnik in 1957 are discussed.

King-Hele, D.

1992-01-01

121

Orbits of 6 Binaries  

NASA Astrophysics Data System (ADS)

In this paper the orbits of binaries WDS 10093+2020 = A 2145, WDS 21074-0814 = BU 368 AB and WDS 22288-0001 = STF 2909 AB are recalculated because of significant deviations of more recent observations from the ephemerides. For binaries WDS 22384-0754 = A 2695, WDS 23474-7118 = FIN 375 Aa and WDS 23578+2508 = McA 76 the orbital elements are calculated for the first time.

Olevic, D.; Cvetkovic, Z.

122

Pediatric Orbital Fractures  

PubMed Central

It is wise to recall the dictum “children are not small adults” when managing pediatric orbital fractures. In a child, the craniofacial skeleton undergoes significant changes in size, shape, and proportion as it grows into maturity. Accordingly, the craniomaxillofacial surgeon must select an appropriate treatment strategy that considers both the nature of the injury and the child's stage of growth. The following review will discuss the management of pediatric orbital fractures, with an emphasis on clinically oriented anatomy and development. PMID:24436730

Oppenheimer, Adam J.; Monson, Laura A.; Buchman, Steven R.

2013-01-01

123

Overall view of the Orbiter Servicing Structure within the Orbiter ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Overall view of the Orbiter Servicing Structure within the Orbiter Processing Facility at Kennedy Space Center. Can you see any hint of the Orbiter Discovery? It is in there. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

124

Definition of molecular orbitals in fragment molecular orbital method  

NASA Astrophysics Data System (ADS)

We propose an explicit definition of molecular orbitals in the fragment molecular orbital (FMO) method. We evaluated the accuracy of this method by using a conventional MO method and the FMO method to compare the calculated molecular orbitals and their orbital energies for four poly glycine molecules. These comparisons show that the molecular orbitals and their orbital energies calculated with the FMO method are within about 1% difference of those calculated with the conventional method. Therefore, the molecular orbitals calculated with the FMO method can be used for accurate calculations of chemical properties of large molecules.

Inadomi, Yuichi; Nakano, Tatsuya; Kitaura, Kazuo; Nagashima, Umpei

2002-09-01

125

Mars Geoscience Orbiter and Lunar Geoscience Orbiter  

NASA Technical Reports Server (NTRS)

The feasibility of using the AE/DE Earth orbiting spacecraft design for the LGO and/or MGO missions was determined. Configurations were developed and subsystems analysis was carried out to optimize the suitability of the spacecraft to the missions. The primary conclusion is that the basic AE/DE spacecraft can readily be applied to the LGO mission with relatively minor, low risk modifications. The MGO mission poses a somewhat more complex problem, primarily due to the overall maneuvering hydrazine budget and power requirements of the sensors and their desired duty cycle. These considerations dictate a modification (scaling up) of the structure to support mission requirements.

Fuldner, W. V.; Kaskiewicz, P. F.

1983-01-01

126

The orbits in cancer imaging  

PubMed Central

Primary malignant lesions in the orbit are relatively uncommon. However, the orbits are frequently involved in haematogeneous metastasis or by direct extension from malignancies originating from the adjacent nasal cavity or paranasal sinuses. This paper focuses on the more commonly encountered primary orbital malignancies and the mapping of tumour spread into the orbits. PMID:17114076

Chong, V F H

2006-01-01

127

Copernicus, medicine, and the heliocentric concept.  

PubMed

With his back to the academically poorly oriented times of medieval Europe, Copernicus, the medical man, led the world into a concept of infinite space. His revolutionary concepts of astrophysics formed a buttress for the efforts of his successors. He looked to the stars, but he also had time to look at and help man. PMID:6351269

Miller, J M

1983-09-01

128

Design of low-energy transfer from lunar orbit to asteroid in the Sun-Earth-Moon system  

NASA Astrophysics Data System (ADS)

Asteroid exploration trajectories which start from a lunar orbit are investigated in this work. It is assumed that the probe departs from lunar orbit and returns to the vicinity of Earth, then escapes from the Earth by performing a perigee maneuver. A low-energy transfer in Sun-Earth-Moon system is adopted. First, the feasible region of low-energy transfer from lunar orbit to perigee within 5 000 km height above the Earth surface in Sun-Earth-Moon system is calculated and analyzed. Three transfer types are found, i.e., large maneuver and fast transfers, small maneuver and fast transfers, and disordered and slow transfers. Most of feasibility trajectories belong to the first two types. Then, the low-energy trajectory leg from lunar orbit to perigee and a heliocentric trajectory leg from perigee to asteroid are patched by a perigee maneuver. The optimal full-transfer trajectory is obtained by exploiting the differential evolution algorithm. Finally, taking 4179 Toutatis asteroid as the target, some low-energy transfer trajectories are obtained and analyzed.

Wang, Ya-Min; Qiao, Dong; Cui, Ping-Yuan

2014-12-01

129

Mars Telecommunications Orbiter, Artist's Concept  

NASA Technical Reports Server (NTRS)

This illustration depicts a concept for NASA's Mars Telecommunications Orbiter in flight around Mars. The orbiter is in development to be the first spacecraft with a primary function of providing communication links while orbiting a foreign planet. The project's plans call for launch in September 2009, arrival at Mars in August 2010 and a mission of six to 10 years while in orbit. Mars Telecommunication Orbiter would serve as the Mars hub for an interplanetery Internet, greatly increasing the information payoff from other future Mars missions. The mission is designed to orbit Mars more than 10 times farther from the planet than orbiters dedicated primarily to science. The high-orbit design minimizes the time that Mars itself blocks the orbiter from communicating with Earth and maximizes the time that the orbiter is above the horizon -- thus capable of communications relay -- for rovers and stationary landers on Mars' surface.

2005-01-01

130

Sedna Orbit Comparisons  

NASA Technical Reports Server (NTRS)

These four panels show the location of the newly discovered planet-like object, dubbed 'Sedna,' which lies in the farthest reaches of our solar system. Each panel, moving counterclockwise from the upper left, successively zooms out to place Sedna in context. The first panel shows the orbits of the inner planets, including Earth, and the asteroid belt that lies between Mars and Jupiter. In the second panel, Sedna is shown well outside the orbits of the outer planets and the more distant Kuiper Belt objects. Sedna's full orbit is illustrated in the third panel along with the object's current location. Sedna is nearing its closest approach to the Sun; its 10,000 year orbit typically takes it to far greater distances. The final panel zooms out much farther, showing that even this large elliptical orbit falls inside what was previously thought to be the inner edge of the Oort cloud. The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than scientists believed.

2004-01-01

131

Orbital Fluid Resupply Assessment  

NASA Technical Reports Server (NTRS)

Orbital fluid resupply can significantly increase the cost-effectiveness and operational flexibility of spacecraft, satellites, and orbiting platforms and observatories. Reusable tankers are currently being designed for transporting fluids to space. A number of options exist for transporting the fluids and propellant to the space-based user systems. The fluids can be transported to space either in the Shuttle cargo bay or using expendable launch vehicles (ELVs). Resupply can thus be accomplished either from the Shuttle bay, or the tanker can be removed from the Shuttle bay or launched on an ELV and attached to a carrier such as the Orbital Maneuvering Vehicle (OMV) or Orbital Transfer Vehicle (OTV) for transport to the user to be serviced. A third option involves locating the tanker at the space station or an unmanned platform as a quasi-permanent servicing facility or depot which returns to the ground for recycling once its tanks are depleted. Current modular tanker designs for monopropellants, bipropellants, and water for space station propulsion are discussed. Superfluid helium tankers are addressed, including trade-offs in tanker sizes, shapes to fit the range of ELVs currently available, and boil-off losses associated with longer-term (greater than 6-month) space-basing. It is concluded that the mixed fleet approach to on-orbit consumables resupply offers significant advantages to the overall logistics requirements.

Eberhardt, Ralph N.

1989-01-01

132

Management of orbital tumors.  

PubMed

Orbital tumors are uncommon. In children, both malignant and benign causes of orbital proptosis necessitate urgent assessment; in many cases, emergent intervention is necessary to avoid blindness. In adults, proptosis is most commonly associated with thyroid orbitopathy. Orbital tumors in adults rarely are characterized by the explosive growth and damage that can occur with childhood lesions. In both age-groups, the evolution of better scanning modalities, such as magnetic resonance imaging with fat saturation and gadolinium enhancement, has improved diagnostic accuracy, especially in patients with loss of vision. In more than 95% of cases, noninvasive techniques yield a correct diagnosis. In patients who require nonsurgical intervention, especially if the diagnosis is uncertain, fine-needle aspiration biopsy has an accuracy that exceeds 95%. Combined-modality therapy has improved the control of and decreased the morbidity associated with several orbital tumors. Surgical advances, such as the ancillary use of the CO2 laser, have enhanced the management of some orbital tumors. PMID:8231272

Char, D H

1993-11-01

133

Arenstorf Orbit JS Model  

NSDL National Science Digital Library

Arenstorf orbits are closed trajectories of the restricted three-body problem. That is, two bodies of masses µ and 1-µ moving in a circular rotation, and a third body of negligible mass moving in the same plane. The computation of these orbits is very sensible to small errors and are a good test for the accuracy of numerical methods for solving Ordinary Differential Equations. This simulation compares the solution of two of these orbits using both a 4th-order fixed step and a 5(4) variable step Runge-Kutta algorithm. The adaptive solver uses an event to find the period of the orbit and stop there. Both the computations of the adaptive solver and the event are done with the step size and the tolerance indicated. The Arenstorf Orbit JS Model was developed using the Easy Java Simulations (Ejs) version 5. It is distributed as a ready-to-run html page and requires only a browser with JavaScript support.

Franciscouembre

2013-08-28

134

Orbit utilization - Current regulations  

NASA Astrophysics Data System (ADS)

It is pointed out that an increasingly efficient use of the geostationary satellite orbit and spectrum is necessary to accommodate the growing number of planned U.S. domestic satellites, as well as those of other countries. Technical efficiency can be maximized by designing satellites in a homogeneous manner which minimizes transmission differences between satellites. However, flexibility is also needed to design domestic satellite facilities to respond to the diverse demands in a competitive market. The Federal Communication Commission (FCC) seeks to achieve a balance between these goals in their domestic satellite policies and regulations. In December 1980, the FCC authorized the construction of some 22 new domestic satellites and the launch of 18 satellites. Attention is given to orbit use policies and reduced orbital spacings.

Lepkowski, R. J.

135

Pioneer Venus orbiter  

NASA Technical Reports Server (NTRS)

The orbiter mission of the Pioneer Venus probe is discussed. In accordance with the low-cost Pioneer Venus concept, NASA intends to use the same basic spacecraft, known as the bus, for the execution of the two missions. The bus will be equipped with all of the subsystems common to the probe and orbiter missions (for example, thermal control, solar cells and power supply, attitude measurement and control, telemetry and communication electronics, and auxiliary propulsion unit). For the 1977 mission, the bus will be equipped with the large and small probes and a special antenna system. For the orbiter mission, the bus will be equipped with a retro-propulsion motor and a high-gain antenna. A diagram of the system envisaged is shown.

1974-01-01

136

On triangulated orbit categories.  

E-print Network

We show that the category of orbits of the bounded derived category of a hereditary category under a well-behaved autoequivalence is canonically triangulated. This answers a question by A. Buan, R. Marsh and I. Reiten which appeared in their study with M. Reineke and G. Todorov of the link between tilting theory and cluster algebras (closely related to work by Caldero-Chapoton-Schiffler) and a question by H. Asashiba about orbit categories. We observe that the resulting triangulated orbit categories provide many easy examples of triangulated categories with the Calabi-Yau property. These include the category of projective modules over a preprojective algebra of generalized Dynkin type in the sense of Happel-Preiser-Ringel, whose triangulated structure goes back to Auslander-Reiten's work on the representation-theoretic approach to rational singularities.

Bernhard Keller

137

Elliptical vs Circular Orbit  

NSDL National Science Digital Library

Find the contrast between a highly exaggerated earth elliptical orbit and circular orbit depicted in .mov format. It should be mentioned to students that in reality the earth's elliptical orbit around the sun would hardly be noticeable if viewed from this distance. Taken alone, the video could unfortunately perpetuate the misconception that earth sun distance is responsible for the seasons. Still, the video is useful for pointing out that the earth's speed around the sun is not constant, with the earth moving fastest in January and slowest in July. This phenomenon helps explain why summer is longer in the Northern Hemisphere and for the analemma. The animation can be paused and rewound to emphasize important points.

Bob Urschel

138

Mars Orbiter Laser Altimeter  

NASA Technical Reports Server (NTRS)

The objective of this study was to support the rebuild and implementation of the Mars Orbiter Laser Altimeter (MOLA) investigation and to perform scientific analysis of current Mars data relevant to the investigation. The instrument is part of the payload of the NASA Mars Global Surveyor (MGS) mission. The instrument is a rebuild of the Mars Observer Laser Altimeter that was originally flown on the ill-fated Mars Observer mission. The instrument is currently in orbit around Mars and has so far returned remarkable data.

Zuber, Maria T.

1997-01-01

139

Trajectories and Orbits  

NSDL National Science Digital Library

Materials presented here outline some basic concepts associated with space flight. Users can read about orbits and the difference between an orbit and a trajectory, escape velocities for Earth and some planets, launch velocities and transit times for interplanetary flights, and the effects of time dilation for astronauts travelling at near-light speeds. This is part of the famous Rand corporation study that was commissioned by Congress in 1958 after the Soviet Union stunned the world by launching Sputnik, the world's first artificial satellite.

140

Satellite orbit predictor  

NASA Technical Reports Server (NTRS)

An analog aid to determine satellite coverage of Emergency Locator Transmitters Emergency Position Indicating Radio Beacon (ELT/EPIRB) distress incidence is discussed. The satellite orbit predictor is a graphical aid for determining the relationship between the satellite orbit, antenna coverage of the spacecraft and coverage of the Local User Terminal. The predictor allows the user to quickly visualize if a selected position will probably be detected and is composed of a base map and a satellite track overlay for each satellite.A table of equator crossings for each satellite is included.

Friedman, Morton l.; Garrett, James, Major

141

[A Roman orbital implant?].  

PubMed

During an excavation in Regensburg/Germany the skeleton of an approximately 20-year-old Roman man was found who was buried in the 3rd/4th century after Christ. A "stone" was found which fitted into the left orbit precisely. After a thorough investigation of the "stone" and with the ophthalmohistorical literature in mind an orbital "implant" as well as a petrified medical paste ("Kollyrium") could be ruled out almost with certainty. Possibly the "stone" served another medical purpose or was used for protection of the eye. PMID:23011607

Rohrbach, J M; Harbeck, M; Holzhauser, P; Tekeva-Rohrbach, C I; Mach, M; Codreanu-Windauer, S

2012-11-01

142

Theory of Orbits  

Microsoft Academic Search

This textbook treats Celestial Mechanics as well as Stellar Dynamics from the common point of view of orbit theory making use of the concepts and techniques from modern geometric mechanics. It starts with elementary Newtonian Mechanics and ends with the dynamics of chaotic motions. The book is meant for students in astronomy and physics alike. Prerequisite is a physicist's knowledge

Dino Boccaletti; Giuseppe Pucacco

1996-01-01

143

On triangulated orbit categories  

Microsoft Academic Search

We show that the category of orbits of the bounded derived category of a hereditary category under a well-behaved autoequivalence is canonically triangulated. This answers a question by A. Buan, R. Marsh and I. Reiten which appeared in their study with M. Reineke and G. Todorov of the link between tilting theory and cluster algebras (closely related to work by

Bernhard Keller

2005-01-01

144

Mars Climate Orbiter  

NASA Technical Reports Server (NTRS)

The Mars Surveyor '98 Climate Orbiter is shown here during acoustic tests that simulate launch conditions. The orbiter was to conduct a two year primary mission to profile the Martian atmosphere and map the surface. To carry out these scientific objectives, the spacecraft carried a rebuilt version of the pressure modulated infrared radiometer, lost with the Mars Observer spacecraft, and a miniaturized dual camera system the size of a pair of binoculars, provided by Malin Space Science Systems, Inc., San Diego, California. During its primary mission, the orbiter was to monitor Mars atmosphere and surface globally on a daily basis for one Martian year (two Earth years), observing the appearance and movement of atmospheric dust and water vapor, as well as characterizing seasonal changes of the planet's surface. Imaging of the surface morphology would also provide important clues about the planet's climate in its early history. The mission was part of NASA's Mars Surveyor program, a sustained program of robotic exploration of the red planet, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. Lockheed Martin Astronautics was NASA's industrial partner in the mission. Unfortunately, Mars Climate Orbiter burned up in the Martian atmosphere on September 23, 1999, due to a metric conversion error that caused the spacecraft to be off course.

1998-01-01

145

Orbital Forces: Teacher Page  

NSDL National Science Digital Library

This activity demonstates orbital motions and forces using a tennis ball swung by a ribbon (this activity should be done outside). The Teacher Page contains background information, tennis ball preparation instructions, and wrap up information. This activity is part of Exploring Planets in the Classroom's Planetary Properties series.

146

Orbital Forces: Student Page  

NSDL National Science Digital Library

This activity teaches students about orbital motions and forces using a tennis ball swung by a ribbon. Students answer the question "What happens when you let the ball go?" Background information, activity procedures, and key words are provided. This activity is part of Exploring Planets in the Classroom's Planetary Properties series.

147

Sedna Orbit Animation  

NASA Technical Reports Server (NTRS)

This animation shows the location of the newly discovered planet-like object, dubbed 'Sedna,' in relation to the rest of the solar system. Starting at the inner solar system, which includes the orbits of Mercury, Venus, Earth, and Mars (all in yellow), the view pulls away through the asteroid belt and the orbits of the outer planets beyond (green). Pluto and the distant Kuiper Belt objects are seen next until finally Sedna comes into view. As the field widens the full orbit of Sedna can be seen along with its current location. Sedna is nearing its closest approach to the Sun; its 10,000 year orbit typically takes it to far greater distances. Moving past Sedna, what was previously thought to be the inner edge of the Oort cloud appears. The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than scientists believed.

2004-01-01

148

Goddard Brouwer Orbit Bulletin  

NASA Technical Reports Server (NTRS)

The bulletin provides operational support for earth space research and technological missions by producing a tape containing pertinent spacecraft orbital information which is provided to a number of cities around the world in support of individual missions. A program description of the main and associated subroutines, and a complete description of the input, output and requirements of the bulletin program are presented.

Morgan, D. B.; Gordon, R. A.

1971-01-01

149

A Neptune Orbiter Mission  

NASA Technical Reports Server (NTRS)

This paper describes the results of new analyses and mission/system designs for a low cost Neptune Orbiter mission. Science and measurement objectives, instrumentation, and mission/system design options are described and reflect an aggressive approach to the application of new advanced technologies expected to be available and developed over the next five to ten years.

Wallace, R. A.; Spilker, T. R.

1998-01-01

150

Close up view of the Orbiter Discovery in the Orbiter ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close up view of the Orbiter Discovery in the Orbiter Processing Facility at Kennedy Space Center. The view is a detail of the aft, starboard landing gear and a general view of the Thermal Protection System tiles around the landing-gear housing. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

151

SPECS: Orbital debris removal  

NASA Technical Reports Server (NTRS)

The debris problem has reached a stage at which the risk to satellites and spacecraft has become substantial in low Earth orbit (LEO). This research discovered that small particles posed little threat to spacecraft because shielding can effectively prevent these particles from damaging the spacecraft. The research also showed that, even though collision with a large piece of debris could destroy the spacecraft, the large pieces of debris pose little danger because they can be tracked and the spacecraft can be maneuvered away from these pieces. Additionally, there are many current designs to capture and remove large debris particles from the space environment. From this analysis, it was decided to concentrate on the removal of medium-sized orbital debris, that is, those pieces ranging from 1 cm to 50 cm in size. The current design incorporates a transfer vehicle and a netting vehicle to capture the medium-sized debris. The system is based near an operational space station located at 28.5 deg inclination and 400 km altitude. The system uses ground-based tracking to determine the location of a satellite breakup or debris cloud. These data are uploaded to the transfer vehicle, which proceeds to rendezvous with the debris at a lower altitude parking orbit. Next, the netting vehicle is deployed, tracks the targeted debris, and captures it. After expending the available nets, the netting vehicle returns to the transfer vehicle for a new netting module and continues to capture more debris in the target area. Once all the netting modules are expended, the transfer vehicle returns to the space station's orbit where it is resupplied with new netting modules from a space shuttle load. The new modules are launched by the shuttle from the ground and the expended modules are taken back to Earth for removal of the captured debris, refueling, and repacking of the nets. Once the netting modules are refurbished, they are taken back into orbit for reuse. In a typical mission, the system has the ability to capture 50 pieces of orbital debris. One mission will take approximately six months and the system is designed to allow for a 30 deg inclination change on the outgoing and incoming trips of the transfer vehicle.

1991-01-01

152

Optimal periodic relative orbit and rectilinear relative orbits with eccentric reference orbits  

NASA Astrophysics Data System (ADS)

The problem of two-body linearized periodic relative orbits with eccentric reference orbits is studied in this paper. The periodic relative orbit in the target-orbital coordinate system can be used in fly-around and formation-flying orbit design. Based on the closed-form solutions to the Tschauner-Hempel equations, the initial condition for periodic relative orbits is obtained. Then the minimum-fuel periodic-orbit condition with a single impulse is analytically derived for given initial position and velocity vectors. When considering the initial coasting time, the impulse position of the global minimum-fuel periodic orbit is proved to be near to the perigee of the target and can be obtained by numerical optimization algorithms. Moreover, the condition for a special periodic orbit, i.e., the rectilinear relative orbit in the target-orbital frame, is obtained. Numerical simulations are used to demonstrate the efficacy of the method, and show the geometry of the periodic relative orbit and the rectilinear relative orbit.

Zhang, Gang; Zhou, Di; Sun, Zhaowei; Cao, Xibin

2013-10-01

153

On initial orbit determination  

NASA Technical Reports Server (NTRS)

The classical methods of initial orbit determination are brought together within a larger viewpoint. This new synthesis stresses that all such techniques follow one of three approaches. Either they seek to compute the orbital element set, or its equivalent, by attacking the differential equations of motion (Laplace), the first integrals of the equations of motion (Taff), or the solution itself (Gauss). The particular technique pursued within a given type of approach should depend upon the nature of the observational data, the amount of a priori information one is willing to presume, and the object of the exercise. This might be a binary star system, a moon, a minor planet, or an artificial satellite. The efficacy of some algorithms for each approach is discussed briefly. Unfortunately, none of them work very well. Extensions of these techniques to radars or laser radars are trivial and have provided no new insights into the overall problem.

Taff, L. G.

1984-01-01

154

Orbital rhabdomyosarcomas: A review  

PubMed Central

Rhabdomyosarcoma (RMS) is a highly malignant tumor and is one of the few life-threatening diseases that present first to the ophthalmologist. It is the most common soft-tissue sarcoma of the head and neck in childhood with 10% of all cases occurring in the orbit. RMS has been reported from birth to the seventh decade, with the majority of cases presenting in early childhood. Survival has changed drastically over the years, from 30% in the 1960’s to 90% presently, with the advent of new diagnostic and therapeutic modalities. The purpose of this review is to provide a general overview of primary orbital RMS derived from a literature search of material published over the last 10 years, as well as to present two representative cases of patients that have been managed at our institute. PMID:24227982

Jurdy, Lama; Merks, Johanus H.M.; Pieters, Bradly R.; Mourits, Maarten P.; Kloos, Roel J.H.M.; Strackee, Simone D.; Saeed, Peerooz

2013-01-01

155

Orbit Spaces in Superconductivity  

E-print Network

In the framework of Landau theory of phase transitions one is interested to describe all the possible low symmetry ``superconducting'' phases allowed for a given superconductor crystal and to determine the conditions under which this crystal undergoes a phase transition. These problems are best described and analyzed in the orbit space of the high symmetry group of the ``normal, non-superconducting'' phase of the crystal. In this article it is worked out a simple example concerning superconductivity, that shows the P-matrix method to determine the equations and inequalities defining the orbit space and its stratification. This approach is of general validity and can be used in all physical problems that make use of invariant functions, as long as the symmetry group is compact.

Vittorino Talamini

2006-07-30

156

Mercury orbiter transport study  

NASA Technical Reports Server (NTRS)

A data base and comparative performance analyses of alternative flight mode options for delivering a range of payload masses to Mercury orbit are provided. Launch opportunities over the period 1980-2000 are considered. Extensive data trades are developed for the ballistic flight mode option utilizing one or more swingbys of Venus. Advanced transport options studied include solar electric propulsion and solar sailing. Results show the significant performance tradeoffs among such key parameters as trip time, payload mass, propulsion system mass, orbit size, launch year sensitivity and relative cost-effectiveness. Handbook-type presentation formats, particularly in the case of ballistic mode data, provide planetary program planners with an easily used source of reference information essential in the preliminary steps of mission selection and planning.

Friedlander, A. L.; Feingold, H.

1977-01-01

157

Orbiter OMS and RCS technology  

NASA Technical Reports Server (NTRS)

Orbiter Orbital Maneuver Subsystem (OMS) and Reaction Control Subsystem (RCS) tankage has proved to be highly successful in shuttle flights on-orbit propellant transfer tests were done. Tank qualification tests along with flight demonstrations were carried out future uses of storable propellants are cited.

Boudreaux, R. A.

1982-01-01

158

Global Orbit Corrections Keith Symon  

E-print Network

Global Orbit Corrections Keith Symon LS-I0l November 1987 K. Symon I. Introduction. There are various reasons for preferring local (e.g., three-bump) orbit correction methods to global corrections this point needs to be tested. Otherwise, some other correction scheme will be needed to bring the orbit

Kemner, Ken

159

What is a MISR orbit?  

... an altitude of 705 km above sea level on a sun-synchronous orbit. It revolves once around the planet in 98.88 minutes and thus completes ... data exploitation, each complete revolution is called an orbit, and orbits are consecutively numbered from launch. The number of the ...

2014-12-08

160

Orbital changes and climate  

Microsoft Academic Search

At the 41,000-period of orbital tilt, summer insolation forces a lagged response in northern ice sheets. This delayed ice signal is rapidly transferred to nearby northern oceans and landmasses by atmospheric dynamics. These ice-driven responses lead to late-phased changes in atmospheric CO2 that provide positive feedback to the ice sheets and also project ‘late’ 41-K forcing across the tropics and

William F. Ruddiman

2006-01-01

161

Interplanetary orbit determination  

NASA Technical Reports Server (NTRS)

The logistical aspects of orbit determination (OD) in the interplanetary phase of the Mariner Mars 1971 mission are described and the working arrangements for the OD personnel, both within the Navigation Team and with outside groups are given. Various types of data used in the OD process are presented along with sources of the data. Functional descriptions of the individual elements of the OD software and brief sketches of their modes of operation are provided.

Zielenbach, J. W.; Acton, C. H.; Born, G. H.; Breckenridge, W. G.; Chao, C. C.; Duxbury, T. C.; Green, D. W.; Jerath, N.; Jordan, J. F.; Mottinger, N. A.

1973-01-01

162

Spectrophotovoltaic orbital power generation  

NASA Technical Reports Server (NTRS)

The feasibilty of a spectrophotovoltaic orbital power generation system that optically concentrates solar energy is demonstrated. A dichroic beam-splitting mirror is used to divide the solar spectrum into two wavebands. Absorption of these wavebands by GaAs and Si solar cell arrays with matched energy bandgaps increases the cell efficiency while decreasing the amount of heat that must be rejected. The projected cost per peak watt if this system is $2.50/W sub p.

Onffroy, J. R.

1980-01-01

163

Small Mercury Relativity Orbiter  

NASA Technical Reports Server (NTRS)

The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.

Bender, Peter L.; Vincent, Mark A.

1989-01-01

164

Orbital drilling kinematics  

Microsoft Academic Search

In orbital drilling the tool (special end mill) moves relative to the work piece on a helical course. Because of the three-dimensional\\u000a tool path and the superimposed rotary cutting motion a complex machining motion results which determines the contact conditions\\u000a of the tool. The objective of this study is to describe mathematically the occurring cutting conditions over the engagement\\u000a angle

E. Brinksmeier; Sascha Fangmann; I. Meyer

2008-01-01

165

Orbital Debris Modeling  

NASA Technical Reports Server (NTRS)

Presentation outlne: (1) The NASA Orbital Debris (OD) Engineering Model -- A mathematical model capable of predicting OD impact risks for the ISS and other critical space assets (2) The NASA OD Evolutionary Model -- A physical model capable of predicting future debris environment based on user-specified scenarios (3) The NASA Standard Satellite Breakup Model -- A model describing the outcome of a satellite breakup (explosion or collision)

Liou, J. C.

2012-01-01

166

Earth Co-orbital Objects  

NASA Astrophysics Data System (ADS)

The recent discovery of asteroid 2002 AA29 by the LINEAR survey and the realization of its co-orbital relationship with Earth lead us to consider the characteristics of Earth Co-orbital Objects (ECOs) in general. An object with semimajor axis between 0.99 and 1.01 AU is in 1:1 resonance with the Earth. To be co-orbital in the sense of moving along the Earth's orbit, an object must further have its other orbital parameters similar to those of the Earth. Clarification is needed as to what range of orbital parameters can be regarded as similar enough to permit classification as an ECO. ECOs would be expected to librate on tadpole or horseshoe orbits, be relatively easy to access with spacecraft, and to sometimes exhibit quasisatellite behavior. 2002 AA29 is on a horseshoe orbit and was discovered in a general asteroid survey while near Earth at one end of the horseshoe orbit. Searches for Earth Trojan asteroids, which would be members of the ECO class on tadpole orbits near a triangular Lagrange Point, have not yet been successful. While 2002 AA29 has an orbit even less eccentric than Earth's, it has an inclination of about 10 degrees. 2000 PH5 and 2001 GO2 are on horseshoe orbits and interact gravitationally with Earth to 'bounce' when they approach the Earth from either side. With eccentricities of .23 and .17 respectively, they do not have decidedly Earth-like orbits despite inclinations less that 5 degrees. When in quasi-satellite mode, a body exhibits a looping motion relative to Earth in some ways resembling a satellite orbit. Several resonant bodies including 3753 Cruithne exhibit this behavior at times, but ECOs remain close to Earth while doing it. We suggest that directed searches be used to discover ECOs and characterize this class of objects. Orbital simulations suggest the best target spaces, which are only partially covered by present general searches.

Wiegert, P.; Connors, M.; Chodas, P.; Veillet, C.; Mikkola, S.; Innanen, K.

2002-12-01

167

Global Orbit Feedback in RHIC  

SciTech Connect

For improved reproducibility of good operating conditions and ramp commissioning efficiency, new dual-plane slow orbit feedback during the energy ramp was implemented during run-10 in the Relativistic Heavy Ion Collider (RHIC). The orbit feedback is based on steering the measured orbit, after subtraction of the dispersive component, to either a design orbit or to a previously saved reference orbit. Using multiple correctors and beam position monitors, an SVD-based algorithm is used for determination of the applied corrections. The online model is used as a basis for matrix computations. In this report we describe the feedback design, review the changes made to realize its implementation, and assess system performance.

Minty, M.; Hulsart, R.; Marusic, A.; Michnoff, R.; Ptitsyn, V.; Robert-Demolaize, G.; Satogata, T.

2010-05-23

168

Viking orbiter attitude control analysis  

NASA Technical Reports Server (NTRS)

Two Viking orbiters are currently in Mars orbit. In the nearly two years since they were launched, the orbiters have successfully performed many functions including transportation of the Viking landers to Mars. The orbiters have for the last year provided relay links for lander-earth communications, and they have carried out from orbit their own scientific exploration of the planet. Crucial to the success of the orbiters has been the performance of the on-board attitude control system, which has provided the required orbiter stabilization and orientation throughout the missions. A comprehensive spacecraft and attitude control system dynamic analysis was necessary to certify the control system before launch and to evaluate its flight performance. This paper contains an outline of the analysis and of some of its results.

Rodriguez, G.

1977-01-01

169

Orbital Phase Environments and Stereoselectivities  

NASA Astrophysics Data System (ADS)

Facial selections are reviewed to propose a new theory, orbital phase environment, for stereoselectivities of organic reactions. The orbital phase environment is a generalized idea of the secondary orbital interaction between the non-reacting centers and the unsymmetrization of the orbitals at the reacting centers arising from in-phase and out-of-phase overlapping with those at the neighboring non-reacting sites. In this context, the nucleophilic addition preferentially occurs on the face of the carbonyl functionality opposite to the better electron-donating orbital at the ? position. In a similar manner to the carbonyl cases, the preferred reaction faces of olefins in electrophilic addition reactions are opposite to the better electron-donating orbitals at the ? positions. The orbital phase environments in Diels-Alder reactions are also reviewed.

Ohwada, Tomohiko

170

Galactic Habitable Orbits  

NASA Astrophysics Data System (ADS)

The fossil record shows that the Earth has experienced several mass extinctions over the past 500 million years1, and it has been suggested that there is a periodicity in extinction events on timescales of tens1 and/or hundreds of millions of years. Various hypotheses have been proposed to explain the cause of the mass extinctions, including the suggestion that the Earth's ozone layer may have been destroyed by intense radiation from a nearby supernovae2- 3, exposing the Earth's surface to damaging UV radiation. Recent observations of cores taken from the ocean floor revealed atoms of a very rare isotope of iron (60Fe) believed to have arrived on Earth around 2 million years ago as fallout from a nearby supernovae4. Astronomical evidence for that past supernovae was recently found in the debris of a young cluster of massive stars5, by tracing its past orbit, putting it at the right place at the right time to explain the mild extinction event. Here we report new high-resolution (both in space and time) N-body chemodynamical simulations (carried out with our novel code GCD+6) of the evolution of a model Milky Way Galaxy, tracing the orbit of èsun-like' stars over a 500 million year period, checking the proximity to supernovae throughout the history of the orbit and comparing the times when this occurs with past mass extinctions on Earth. We additionally explain the important effects of the spiral arm pattern, radial migration of stars and Galactic chemistry on habitability.

Rahimi, A.; Mao, S.; Kawata, D.

2014-03-01

171

The Earth's Orbit  

NSDL National Science Digital Library

These eleven activities relate to the results of the motion and position of the Earth in its orbit, investigating both the causes and the effects of changing seasons. It starts simply by trying to quantify the observation that it is colder in the winter and ends by measuring the tilt of the Earth. This is chapter two of the online book Eyes on the Sky, Feet on the Ground, containing explorations into astronomy as a classroom tool for learning how to theorize, experiment, and analyze data. The activities are fully illustrated and contain detailed, step-by-step instructions as well as suggested discussion topics.

2007-12-12

172

Orbital fractures: pathophysiology and implant materials for orbital reconstruction.  

PubMed

Among midfacial fractures, the frequency of orbital injuries is surpassed only by nasal fractures. A clear understanding of orbital anatomy and the pathophysiology of these injuries is critical to accurate diagnosis, precise surgical reconstruction, and successful clinical outcomes. This chapter reviews the mechanism of injury and pathophysiology of orbital fractures as well as the implant materials that are currently used for surgical reconstruction. PMID:25397706

Strong, E Bradley

2014-10-01

173

The orbit properties of colliding co-orbiting bodies  

NASA Technical Reports Server (NTRS)

It is generally assumed that an ensemble of small bodies located in similar Keplarian orbits will, because of collisions, tend to disperse into more and more dissimilar orbits. This theory was challenged. Alfven maintains that for the case where the time between collisions is longer than the orbit period and the collisions are essentially inelastic the orbits and velocities will become more similar. This gives rise to the concepts of negative diffusion and jet streams. It is proposed that this question might be investigated experimentally using the space station. The proposed experiment is briefly described.

Freeman, John W.

1987-01-01

174

General view of the Orbiter Discovery in the Orbiter Processing ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

General view of the Orbiter Discovery in the Orbiter Processing Facility at Kennedy Space Center showing the payload bay doors open exposing the heat-dissipating radiator panels located on the inside of the payload bay doors. Also in the view is the boom portion of the boom sensor system deployed as part of the return to flight procedures after STS-107 to inspect the orbiter's thermal protection system. The Remote Manipulator System, the "Canadarm", and the airlock are seen in the background of the image. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

175

Orbital Evolution and Impact Hazard of Asteroids on Retrograde Orbits  

NASA Astrophysics Data System (ADS)

We present the past evolutional scenarios of known group of asteroids in retrograde orbits. Applying the latest observational data, we determined their nominal and averaged orbital elements. Next, we studied the behaviour of their orbital motion 1~My in the past (100~My in the future for two NEAs) taking into account the limitations of observational errors. It has been shown that the influence of outer planets perturbations in many cases can import small bodies on high inclination or retrograde orbits into the inner Solar System.

Kankiewicz, P.; W?odarczyk, I.

2014-07-01

176

The Košice meteorite fall: Atmospheric trajectory, fragmentation, and orbit  

NASA Astrophysics Data System (ADS)

The Košice meteorite fall occurred in eastern Slovakia on February 28, 2010, 22:25 UT. The very bright bolide was imaged by three security video cameras from Hungary. Detailed bolide light curves were obtained through clouds by radiometers on seven cameras of the European Fireball Network. Records of sonic waves were found on six seismic and four infrasonic stations. An atmospheric dust cloud was observed the next morning before sunrise. After careful calibration, the video records were used to compute the bolide trajectory and velocity. The meteoroid, of estimated mass of 3500 kg, entered the atmosphere with a velocity of 15 km s-1 on a trajectory with a slope of 60° to the horizontal. The largest fragment ceased to be visible at a height of 17 km, where it was decelerated to 4.5 km s-1. A maximum brightness of absolute stellar magnitude about -18 was reached at a height of 36 km. We developed a detailed model of meteoroid atmospheric fragmentation to fit the observed light curve and deceleration. We found that Košice was a weak meteoroid, which started to fragment under the dynamic pressure of only 0.1 MPa and fragmented heavily under 1 MPa. In total, 78 meteorites were recovered in the predicted fall area during official searches. Other meteorites were found by private collectors. Known meteorite masses ranged from 0.56 g to 2.37 kg. The meteorites were classified as ordinary chondrites of type H5 and shock stage S3. The heliocentric orbit had a relatively large semimajor axis of 2.7 AU and aphelion distance of 4.5 ± 0.5 AU. Backward numerical integration of the preimpact orbit indicates possible large variations of the orbital elements in the past due to resonances with Jupiter.

Borovi?Ka, Ji?í; Tóth, Juraj; Igaz, Antal; Spurný, Pavel; Kalenda, Pavel; Haloda, Jakub; Svoreå, Ján; Kornoš, Leonard; Silber, Elizabeth; Brown, Peter; HusáRik, Marek

2013-10-01

177

Mars Observer orbit determination analysis  

NASA Technical Reports Server (NTRS)

Results are presented of a simulated orbit determination analysis for three phases of the Mars Observer mission (interplanetary cruise, orbit insertion, and mapping), together with a summary of orbital accuracies throughout the Mars Observer mission. The plan for achieving the navigation objectives of the Mars Observer mission is described. These objectives are to navigate the Mars Observer spacecraft to Mars and achieve accurate targeting at Mars; to propulsively maneuver the spacecraft into a 3-day period, capture orbit; to navigate the spacecraft into a 1.96-hr period low-altitude, nearly circular mapping orbit; and to maintain Mars Observer in the mapping orbit throughout the 687 days devoted for scientific data acquisition. Factors that will affect the spacecraft during each of the three phases are discussed.

Esposito, Pasquale; Roth, Duane; Demcak, Stuart

1991-01-01

178

N -observations and radar orbits  

Microsoft Academic Search

Initial asteriod orbits are determined by a least squares adjustment of an arbitrary number (N) of optical and radar observations. The usual separation, into an orbit determination by three observations and a subsequent\\u000a differential orbit improvement, is combined into a single algorithm. A priori information is used for very small arcs. Ephemerides\\u000a very suitable for linking are obtained by strictly

Leif Kahl Kristensen

2007-01-01

179

Spectroscopic binaries with elliptical orbits  

E-print Network

The radial velocity curves of many spectroscopic binaries (SBs) are perturbed by gas streams or proximity effects. For SBs with circular orbits, these perturbations can give rise to spurious orbital eccentricities of high statistical significance. But tests to identify such anomalous orbits can be constructed since perturbed velocity curves are in general no longer Keplerian. The derived tests are applied both to synthetic and to observed velocity curves.

L. B. Lucy

2005-05-11

180

Lunar Reconnaissance Orbiter  

NASA Astrophysics Data System (ADS)

NASA's Lunar Reconnaissance Orbiter (LRO) plans to launch in October 2008 with a companion secondary impactor mission, LCROSS, as the inaugural missions for the Exploration System Mission Directorate. LRO is a pathfinder whose objective is to obtain the needed information to prepare for eventual human return to the Moon. LRO will undertake at least one baseline year of operation with additional extended mission phase sponsored by NASA's Science Mission Directorate. LRO will employ six individual instruments to produce accurate maps and high-resolution images of future landing sites, to assess potential lunar resources, and to characterize the radiation environment. LRO will also test the feasibility of one advanced technology demonstration package. The LRO payload includes: Lunar Orbiter Laser Altimeter (LOLA) which will determine the global topography of the lunar surface at high resolution, measure landing site slopes, surface roughness, and search for possible polar surface ice in shadowed regions; Lunar Reconnaissance Orbiter Camera (LROC) which will acquire targeted narrow angle images of the lunar surface capable of resolving meter-scale features to support landing site selection, as well as wide-angle images to characterize polar illumination conditions and to identify potential resources; Lunar Exploration Neutron Detector (LEND) which will map the flux of neutrons from the lunar surface to search for evidence of water ice, and will provide space radiation environment measurements that may be useful for future human exploration; Diviner Lunar Radiometer Experiment (DLRE) which will chart the temperature of the entire lunar surface at approximately 300 meter horizontal resolution to identify cold-traps and potential ice deposits; Lyman-Alpha Mapping Project (LAMP) which will map the entire lunar surface in the far ultraviolet. LAMP will search for surface ice and frost in the polar regions and provide images of permanently shadowed regions illuminated only by starlight; Cosmic Ray Telescope for the Effects of Radiation (CRaTER), which will investigate the effect of galactic cosmic rays on tissue-equivalent plastics as a constraint on models of biological response to background space radiation. The technology demonstration is an advanced radar (mini-RF) that will demonstrate X- and S-band radar imaging and interferometry using a light-weight synthetic aperture radar.

Morgan, T.; Chin, G.

2007-08-01

181

[Orbital granulocytic sarcoma: case report].  

PubMed

Orbital granulocytic sarcoma is a localized tumor consisting of malignant cells of myeloid origin. This tumor may present in association with acute myelogenous leukemia. Granulocytic sarcoma may be found in a variety of locations throughout the body including the orbit and typically affects children and young adults. There is a slight male predominance in these cases. This is an uncommon case report of a 33-year-old Latin-American woman who was admitted to the Hospital for rapidly progressive orbital proptosis. There was no systemic manifestation of leukemia. The occurrence of orbital granulocytic sarcoma before the development of systemic leukemia in children and young adults is not uncommon and these cases frequently develop hematological evidence within 2 months after initial orbital disease. In this case report, there was no systemic manifestation of leukemia in the last 30 months, even in the presence of orbital tumors. Granulocytic sarcoma is most frequently confused with malignant lymphoma, rhabdomyosarcoma and neuroblastoma. The differential diagnosis of these cases can be challenging, particularly when there is no evidence of systemic leukemia, when imaging features are not sufficiently specific to distinguish granulocytic neoplasms from other tumors. To establish the diagnosis often a biopsy is required. The treatment in such cases (orbital granulocytic sarcoma) is not standardized. Orbital granulocytic sarcoma may be suspected in cases of orbital tumors even in the absence of systemic manifestations of leukemia at any age. PMID:16322847

Fonseca Junior, Nilson Lopes da; Paves, Luis; Nakanami, Deise Mitsuko; Seixas, Maria Teresa; Manso, Paulo Góis

2005-01-01

182

OSO-6 Orbiting Solar Observatory  

NASA Technical Reports Server (NTRS)

The description, development history, test history, and orbital performance analysis of the OSO-6 Orbiting Solar Observatory are presented. The OSO-6 Orbiting Solar Observatory was the sixth flight model of a series of scientific spacecraft designed to provide a stable platform for experiments engaged in the collection of solar and celestial radiation data. The design objective was 180 days of orbital operation. The OSO-6 has telemetered an enormous amount of very useful experiment and housekeeping data to GSFC ground stations. Observatory operation during the two-year reporting period was very successful except for some experiment instrument problems.

1972-01-01

183

Geology orbiter comparison study  

NASA Technical Reports Server (NTRS)

Instrument requirements of planetary geology orbiters were examined with the objective of determining the feasibility of applying standard instrument designs to a host of terrestrial targets. Within the basic discipline area of geochemistry, gamma-ray, X-ray fluorescence, and atomic spectroscopy remote sensing techniques were considered. Within the discipline area of geophysics, the complementary techniques of gravimetry and radar were studied. Experiments using these techniques were analyzed for comparison at the Moon, Mercury, Mars and the Galilean satellites. On the basis of these comparative assessments, the adaptability of each sensing technique was judged as a basic technique for many targets, as a single instrument applied to many targets, as a single instrument used in different mission modes, and as an instrument capability for nongeoscience objectives.

Cutts, J. A. J.; Blasius, K. R.; Davis, D. R.; Pang, K. D.; Shreve, D. C.

1977-01-01

184

Orbital magnetic ratchet effect  

NASA Astrophysics Data System (ADS)

Magnetic ratchets—two-dimensional systems with superimposed noncentrosymmetric ferromagnetic gratings—are considered theoretically. It is demonstrated that excitation by radiation results in a directed motion of two-dimensional carriers due to the pure orbital effect of the periodic magnetic field. Magnetic ratchets based on various two-dimensional systems such as topological insulators, graphene, and semiconductor heterostructures are investigated. The mechanisms of the electric current generation caused by both radiation-induced heating of carriers and by acceleration in the radiation electric field in the presence of a space-oscillating Lorentz force are studied in detail. The electric currents sensitive to the linear polarization plane orientation as well as to the radiation helicity are calculated. It is demonstrated that the frequency dependence of the magnetic ratchet currents is determined by the dominant elastic-scattering mechanism of two-dimensional carriers and differs for the systems with linear and parabolic energy dispersions.

Budkin, G. V.; Golub, L. E.

2014-09-01

185

Exploratory orbit analysis  

SciTech Connect

Unlike the other documents in these proceedings, this paper is neither a scientific nor a technical report. It is, rather, a short personal essay which attempts to describe an Exploratory Orbit Analysis (EOA) environment. Analyzing the behavior of a four or six dimensional nonlinear dynamical system is at least as difficult as analyzing events in high-energy collisions; the consequences of doing it badly, or slowly, would be at least as devastating; and yet the level of effort and expenditure invested in the latter, the very attention paid to it by physicists at large, must be two orders of magnitude greater than that given to the former. It is difficult to choose the model which best explains the behavior of a physical device if one does not first understand the behavior of the available models. The time is ripe for the development of a functioning EOA environment, which I will try to describe in this paper to help us achieve this goal.

Michelotti, L.

1989-03-01

186

Orbiting Carbon Observatory  

NASA Technical Reports Server (NTRS)

Human impact on the environment has produced measurable changes in the geological record since the late 1700s. Anthropogenic emissions of CO2 today may cause the global climate to depart for its natural behavior for many millenia. CO2 is the primary anthropogenic driver of climate change. The Orbiting Carbon Observatory goals are to help collect measurements of atmospheric CO2, answering questions such as why the atmospheric CO2 buildup varies annually, the roles of the oceans and land ecosystems in absorbing CO2, the roles of North American and Eurasian sinks and how these carbon sinks respond to climate change. The present carbon cycle, CO2 variability, and climate uncertainties due atmospheric CO2 uncertainties are highlighted in this presentation.

Miller, Charles E.

2005-01-01

187

TOPEX orbital radiation study  

NASA Technical Reports Server (NTRS)

The space radiation environment of the TOPEX spacecraft is investigated. A single trajectory was considered. The external (surface incident) charged particle radiation, predicted for the satellite, is determined by orbital flux integration for the specified trajectory. The latest standard models of the environment are used in the calculations. The evaluation is performed for solar maximum conditions. The spacecraft exposure to cosmic rays of galactic origin is evaluated over its flight path through the magnetosphere in terms of geomagnetic shielding effects, both for surface incident heavy ions and for particles emerging behind different material thickness. Limited shielding and dose evaluations are performed for simple infinite slab and spherical geometries. Results, given in graphical and tabular form, are analyzed, explained, and discussed. Conclusions are presented and commented on.

Stassinopoulos, E. G.; Barth, J. M.

1984-01-01

188

Orbital exenteration--simplified.  

PubMed Central

In summary, a simplified technique of orbital exenteration has been presented. Results, with complications, in eleven cases have been described. The advantages of the operative method described are: (1) full thickness skin provides better cushion for self-retaining prosthesis, (2) skin with intact blood supply is much less likely to be rejected, (3) no donor site with added discomfort and care, (4) local recurrence of neoplasm is easily detected, (5) operating time shortened and (6) favorable patient acceptance. Images FIGURE 8 A FIGURE 8 B FIGURE 9 FIGURE 10 FIGURE 11 A FIGURE 11 B FIGURE 11 C FIGURE 11 D FIGURE 12 FIGURE 13 A FIGURE 13 B FIGURE 14 A FIGURE 14 B FIGURE 15 FIGURE 16 FIGURE 17 PMID:7043863

Coston, T O; Small, R G

1981-01-01

189

Determination of orbits with Torun Orbit Processor system  

Microsoft Academic Search

The Torun Orbit Processor system (TOP) is a multipurpose system designed to provide the research requirements of the various orbital problems for artificial satellites. The analysis of mathematical model for the TOP system began in 1991 and coding for the IBM PC and Sun SparcStation 10 computers was completed in 1993. TOP was first used for laser data processing of

A. Drozyner

1995-01-01

190

A survey of orbits of co-orbitals of Mars  

NASA Astrophysics Data System (ADS)

Many asteroids with a semimajor axis close to that of Mars have been discovered in the last several years. Potentially some of these could be in 1:1 resonance with Mars, much as are the classic Trojan asteroids with Jupiter, and its lesser-known horseshoe companions with Earth. In the 1990s, two Trojan companions of Mars, 5261 Eureka and 1998 VF 31, were discovered, librating about the L 5 Lagrange point, 60° behind Mars in its orbit. Although several other potential Mars Trojans have been identified, our orbital calculations show only one other known asteroid, 1999 UJ 7, to be a Trojan, associated with the L 4 Lagrange point, 60° ahead of Mars in its orbit. We further find that asteroid 36017 (1999 ND 43) is a horseshoe librator, alternating with periods of Trojan motion. This asteroid makes repeated close approaches to Earth and has a chaotic orbit whose behavior can be confidently predicted for less than 3000 years. We identify two objects, 2001 HW 15 and 2000 TG 2, within the resonant region capable of undergoing what we designate "circulation transition", in which objects can pass between circulation outside the orbit of Mars and circulation inside it, or vice versa. The eccentricity of the orbit of Mars appears to play an important role in circulation transition and in horseshoe motion. Based on the orbits and on spectroscopic data, the Trojan asteroids of Mars may be primordial bodies, while some co-orbital bodies may be in a temporary state of motion.

Connors, Martin; Stacey, Greg; Brasser, Ramon; Wiegert, Paul

2005-05-01

191

Orbit Determination Toolbox  

NASA Technical Reports Server (NTRS)

The Orbit Determination Toolbox is an orbit determination (OD) analysis tool based on MATLAB and Java that provides a flexible way to do early mission analysis. The toolbox is primarily intended for advanced mission analysis such as might be performed in concept exploration, proposal, early design phase, or rapid design center environments. The emphasis is on flexibility, but it has enough fidelity to produce credible results. Insight into all flight dynamics source code is provided. MATLAB is the primary user interface and is used for piecing together measurement and dynamic models. The Java Astrodynamics Toolbox is used as an engine for things that might be slow or inefficient in MATLAB, such as high-fidelity trajectory propagation, lunar and planetary ephemeris look-ups, precession, nutation, polar motion calculations, ephemeris file parsing, and the like. The primary analysis functions are sequential filter/smoother and batch least-squares commands that incorporate Monte-Carlo data simulation, linear covariance analysis, measurement processing, and plotting capabilities at the generic level. These functions have a user interface that is based on that of the MATLAB ODE suite. To perform a specific analysis, users write MATLAB functions that implement truth and design system models. The user provides his or her models as inputs to the filter commands. The software provides a capability to publish and subscribe to a software bus that is compliant with the NASA Goddard Mission Services Evolution Center (GMSEC) standards, to exchange data with other flight dynamics tools to simplify the flight dynamics design cycle. Using the publish and subscribe approach allows for analysts in a rapid design center environment to seamlessly incorporate changes in spacecraft and mission design into navigation analysis and vice versa.

Carpenter, James R.; Berry, Kevin; Gregpru. Late; Speckman, Keith; Hur-Diaz, Sun; Surka, Derek; Gaylor, Dave

2010-01-01

192

PyORBIT: A Python Shell For ORBIT  

SciTech Connect

ORBIT is code developed at SNS to simulate beam dynamics in accumulation rings and synchrotrons. The code is structured as a collection of external C++ modules for SuperCode, a high level interpreter shell developed at LLNL in the early 1990s. SuperCode is no longer actively supported and there has for some time been interest in replacing it by a modern scripting language, while preserving the feel of the original ORBIT program. In this paper, we describe a new version of ORBIT where the role of SuperCode is assumed by Python, a free, well-documented and widely supported object-oriented scripting language. We also compare PyORBIT to ORBIT from the standpoint of features, performance and future expandability.

Jean-Francois Ostiguy; Jeffrey Holmes

2003-07-01

193

New orbit correction method uniting global and local orbit corrections  

NASA Astrophysics Data System (ADS)

A new orbit correction method, called the eigenvector method with constraints (EVC), is proposed and formulated to unite global and local orbit corrections for ring accelerators, especially synchrotron radiation(SR) sources. The EVC can exactly correct the beam positions at arbitrarily selected ring positions such as light source points, simultaneously reducing closed orbit distortion (COD) around the whole ring. Computer simulations clearly demonstrate these features of the EVC for both cases of the Super-SOR light source and the Advanced Light Source (ALS) that have typical structures of high-brilliance SR sources. In addition, the effects of errors in beam position monitor (BPM) reading and steering magnet setting on the orbit correction are analytically expressed and also compared with the computer simulations. Simulation results show that the EVC is very effective and useful for orbit correction and beam position stabilization in SR sources.

Nakamura, N.; Takaki, H.; Sakai, H.; Satoh, M.; Harada, K.; Kamiya, Y.

2006-01-01

194

Beyond the periodic orbit theory  

E-print Network

The global constraints on chaotic dynamics induced by the analyticity of smooth flows are used to dispense with individual periodic orbits and derive infinite families of exact sum rules for several simple dynamical systems. The associated Fredholm determinants are of particularly simple polynomial form. The theory developed suggests an alternative to the conventional periodic orbit theory approach to determining eigenspectra of transfer operators.

Predrag Cvitanovic; Kim Hansen; Juri Rolf; Gabor Vattay

1997-12-02

195

The Mars Reconnaissance Orbiter Mission  

Microsoft Academic Search

The Mars Reconnaissance Orbiter (MRO) will be launched in August 2005 by an Atlas V 401 expendable launch vehicle from Cape Canaveral Air Force Station, USA. It will deliver to Mars orbit a payload to conduct remote sensing science observations, identify and characterize sites for future landers, and provide critical telecom\\/navigation relay capability for follow-on missions. The mission is designed

James E. Graf; Richard W. Zurek; Howard J. Eisen; Benhan Jai; M. D. Johnston; Ramon DePaula

2005-01-01

196

Orbital anatomy for the surgeon.  

PubMed

An anatomic description of the orbit and its contents and the eyelids directed toward surgeons is the focus of this article. The bone and soft tissue anatomic nuances for surgery are highlighted, including a section on osteology, muscles, and the orbital suspensory system. Innervation and vascular anatomy are also addressed. PMID:23107426

Turvey, Timothy A; Golden, Brent A

2012-11-01

197

Early History & Fiction! Orbital Motion!  

E-print Network

://www.princeton.edu/~stengel/FRS.html! ·! Decades of the Great Dreams" ·! From the Earth to the Moon, Jules Verne" ·! Equations of Motion of the Great Dreams! Decades of the Great Dreams! #12;Near and Far Sides of the Moon" Clementine mission, 1994-1905)! 1865! Orbital Motion! #12;Orbits 101" Satellites" Escape and Capture (Comets, Meteorites)" Two

Stengel, Robert F.

198

Artificial frozen orbits around Mercury  

NASA Astrophysics Data System (ADS)

Orbits around Mercury are influenced by the strong elliptic third-body perturbation, especially for high eccentricity orbits, the periapsis altitude changes dramatically. Frozen orbits whose mean eccentricity and argument of perigee remain constants are obviously a good choice for space missions, but the forming conditions are too harsh to meet practical needs. To deal with this problem, a continuous control method that combines analytical theory and parameter optimization is proposed to build an artificial frozen orbit. The artificial frozen orbits are investigated on the basis of double averaged Hamiltonian, of which the second and third zonal harmonics and the perturbation of elliptic third-body gravity are considered. In this paper, coefficients of perturbations which satisfy the conditions of frozen orbits are involved as control parameters, and the relevant artificial perturbations are compensated by the control strategy. So probes around Mercury can be kept on frozen orbit under the influence of continuous control force. Then complex method of optimization is used to search for the energy optimized artificial frozen orbits. The choosing of optimal parameters, the objective function setting and other issues are also discussed in the study. Evolution of optimal control parameters are given in large ranges of semi-major axis and eccentricity, through the variation of these curves, the fuel efficiency is discussed. The result shows that the control method proposed in this paper can effectively maintain the eccentricity and argument of perigee frozen.

Ma, Xue; Li, Junfeng

2013-12-01

199

Orbital evolution around irregular bodies  

Microsoft Academic Search

The new profiles of the space missions aimed at asteroids and comets, moving from fly-bys to rendezvous and orbiting, call for new spaceflight dynamics tools capable of propagating orbits in an accurate way around these small irregular objects. Moreover, interesting celestial mechanics and planetary science problems, requiring the same sophisticated tools, have been raised by the first images of asteroids

A. Rossi; F. Marzari; P. Farinella

1999-01-01

200

Chelyabinsk Superbolide: a detailed analysis of the passage through the~atmosphere and orbit determination  

NASA Astrophysics Data System (ADS)

A detailed analysis of the passage through the atmosphere of a very bright meteor that exploded in the air near Chelyabinsk, Russia on February 15, 2013 is presented. A number of videos and photographs were examined thoroughly to determine the meteor trajectory beginning from the recorded atmospheric entry height of about 62.5 km until its disappearance at about 9.8 km. The calculated velocity changes as a function time revealed an unusual behavior: during the first 10 seconds the meteor velocity increased from 16.6 km/s up to about 20.6 km/s in the main air burst at the altitude of 26.5 km. Afterwards it decreased rapidly. The light curves derived from videos enabled the total radiant energy and mass loss variations to be calculated. The heliocentric orbit of the meteoroid and possible parent bodies were computed. We proposed an additional 'close approaches' method to the existing method of checking meteoroid/bolide parent bodies based on different D-criteria.

W?odarczyk, K.; W?odarczyk, I.

2014-07-01

201

Orbit bifurcations and wavefunction autocorrelations  

NASA Astrophysics Data System (ADS)

It was recently shown (Keating J P and Prado S D 2001 Proc. R. Soc. A 457 1855 72) that, in the semiclassical limit, the scarring of quantum eigenfunctions by classical periodic orbits in chaotic systems may be dramatically enhanced when the orbits in question undergo bifurcation. Specifically, a bifurcating orbit gives rise to a scar with an amplitude that scales as hbar? and a width that scales as hbar?, where ? and ? are bifurcation-dependent scar exponents whose values are typically smaller than those (? = ? = ½) associated with isolated and unstable periodic orbits. We here analyse the influence of bifurcations on the autocorrelation function of quantum eigenstates, averaged with respect to energy. It is shown that the length-scale of the correlations around a bifurcating orbit scales semiclassically as hbar1-?, where ? is the corresponding scar amplitude exponent. This imprint of bifurcations on quantum autocorrelations is illustrated by numerical computations for a family of perturbed cat maps.

Bäcker, A.; Keating, J. P.; Prado, S. D.

2002-09-01

202

General relativity and satellite orbits  

NASA Technical Reports Server (NTRS)

The general relativistic correction to the position of a satellite is found by retaining Newtonian physics for an observer on the satellite and introducing a potential. The potential is expanded in terms of the Keplerian elements of the orbit and substituted in Lagrange's equations. Integration of the equations shows that a typical earth satellite with small orbital eccentricity is displaced by about 17 cm. from its unperturbed position after a single orbit, while the periodic displacement over the orbit reaches a maximum of about 3 cm. The moon is displaced by about the same amounts. Application of the equations to Mercury gives a total displacement of about 58 km. after one orbit and a maximum periodic displacement of about 12 km.

Rubincam, D. P.

1975-01-01

203

Lifetimes of lunar satellite orbits  

NASA Technical Reports Server (NTRS)

The Space Exploration Initiative has generated a renewed interest in lunar mission planning. The lunar missions currently under study, unlike the Apollo missions, involve long stay times. Several lunar gravity models have been formulated, but mission planners do not have enough confidence in the proposed models to conduct detailed studies of missions with long stay times. In this report, a particular lunar gravitational model, the Ferrari 5 x 5 model, was chosen to determine the lifetimes for 100-km and 300-km perilune altitude, near-circular parking orbits. The need to analyze orbital lifetimes for a large number of initial orbital parameters was the motivation for the formulation of a simplified gravitational model from the original model. Using this model, orbital lifetimes were found to be heavily dependent on the initial conditions of the nearly circular orbits, particularly the initial inclination and argument of perilune. This selected model yielded lifetime predictions of less than 40 days for some orbits, and other orbits had lifetimes exceeding a year. Although inconsistencies and limitations are inherent in all existing lunar gravity models, primarily because of a lack of information about the far side of the moon, the methods presented in this analysis are suitable for incorporating the moon's nonspherical gravitational effects on the preliminary design level for future lunar mission planning.

Meyer, Kurt W.; Buglia, James J.; Desai, Prasun N.

1994-01-01

204

Radiation therapy for orbital lymphoma  

SciTech Connect

Purpose: To describe radiation techniques and evaluate outcomes for orbital lymphoma. Methods and Materials: Forty-six patients (and 62 eyes) with orbital lymphoma treated with radiotherapy between 1987 and 2003 were included. The majority had mucosa-associated lymphoid tissue (48%) or follicular (30%) lymphoma. Seventeen patients had prior lymphoma at other sites, and 29 had primary orbital lymphoma. Median follow-up was 46 months. Results: The median dose was 30.6 Gy; one-third received <30 Gy. Electrons were used in 9 eyes with disease confined to the conjunctiva or eyelid, and photons in 53 eyes with involvement of intraorbital tissues to cover entire orbit. Local control rate was 98% for all patients and 100% for those with indolent lymphoma. Three of the 26 patients with localized primary lymphoma failed distantly, resulting in a 5-year freedom-from-distant-relapse rate of 89%. The 5-year disease-specific and overall survival rates were 95% and 88%, respectively. Late toxicity was mainly cataract formation in patients who received radiation without lens block. Conclusions A dose of 30 Gy is sufficient for indolent orbital lymphoma. Distant relapse rate in patients with localized orbital lymphoma was lower than that reported for low-grade lymphoma presenting in other sites. Orbital radiotherapy can be used for salvage of recurrent indolent lymphoma.

Zhou Ping [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States)]. E-mail: pzhou@partners.org; Ng, Andrea K. [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States); Silver, Barbara [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States); Li Sigui [Department of Biostatistical Sciences, Dana-Farber Cancer Institute, Boston, MA (United States); Hua Ling [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States); Mauch, Peter M. [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States)

2005-11-01

205

Orbital, Rotational, and Climatic Interactions  

NASA Technical Reports Server (NTRS)

The report of an international meeting on the topic of Orbital, Rotational, and Climatic Interactions, which was held 9-11 Jul. 1991 at the Johns Hopkins University is presented. The meeting was attended by 22 researchers working on various aspects of orbital and rotational dynamics, paleoclimate data analysis and modeling, solid-Earth deformation studies, and paleomagnetic analyses. The primary objective of the workshop was to arrive at a better understanding of the interactions between the orbital, rotational, and climatic variations of the Earth. This report contains a brief introduction and 14 contributed papers which cover most of the topics discussed at the meeting.

Bills, Bruce G. (editor)

1992-01-01

206

Simulation of precise orbit determination of lunar orbiters  

Microsoft Academic Search

Based on the ongoing Chinese lunar exploration mission, i.e. the “Chang'e 1” project, precise orbit determination of lunar orbiters is analyzed for the actual geographical distribution and observational accuracy of the Chinese united S-band (USB) observation and control network as well as the very long baseline interferometry (VLBI) tracking network. The observed data are first simulated, then solutions are found

Xiao-Gong Hu; Cheng Huang; Yong Huang

2005-01-01

207

JSC Orbital Debris Website Description  

NASA Technical Reports Server (NTRS)

Purpose: The website provides information about the NASA Orbital Debris Program Office at JSC, which is the lead NASA center for orbital debris research. It is recognized world-wide for its leadership in addressing orbital debris issues. The NASA Orbital Debris Program Office has taken the international lead in conducting measurements of the environment and in developing the technical consensus for adopting mitigation measures to protect users of the orbital environment. Work at the center continues with developing an improved understanding of the orbital debris environment and measures that can be taken to control its growth. Major Contents: Orbital Debris research is divided into the following five broad efforts. Each area of research contains specific information as follows: 1) Modeling - NASA scientists continue to develop and upgrade orbital debris models to describe and characterize the current and future debris environment. Evolutionary and engineering models are described in detail. Downloadable items include a document in PDF format and executable software. 2) Measurements - Measurements of near-Earth orbital debris are accomplished by conducting ground-based and space-based observations of the orbital debris environment. The data from these sources provide validation of the environment models and identify the presence of new sources. Radar, optical and surface examinations are described. External links to related topics are provided. 3) Protection - Orbital debris protection involves conducting hypervelocity impact measurements to assess the risk presented by orbital debris to operating spacecraft and developing new materials and new designs to provide better protection from the environment with less weight penalty. The data from this work provides the link between the environment defined by the models and the risk presented by that environment to operating spacecraft and provides recommendations on design and operations procedures to reduce the risk as required. These data also help in the analysis and interpretation of impact features on returned spacecraft surfaces. 4) Mitigation - Controlling the growth of the orbital debris population is a high priority for NASA, the United States, and the major space-faring nations of the world to preserve near-Earth space for future generations. Mitigation measures can take the form of curtailing or preventing the creation of new debris, designing satellites to withstand impacts by small debris, and implementing operational procedures ranging from utilizing orbital regimes with less debris, adopting specific spacecraft attitudes, and even maneuvering to avoid collisions with debris. Downloadable items include several documents in PDF format and executable software.and 5) Reentry - Because of the increasing number of objects in space, NASA has adopted guidelines and assessment procedures to reduce the number of non-operational spacecraft and spent rocket upper stages orbiting the Earth. One method of postmission disposal is to allow reentry of these spacecraft, either from orbital decay (uncontrolled entry) or with a controlled entry. Orbital decay may be achieved by firing engines to lower the perigee altitude so that atmospheric drag will eventually cause the spacecraft to enter. However, the surviving debris impact footprint cannot be guaranteed to avoid inhabited landmasses. Controlled entry normally occurs by using a larger amount of propellant with a larger propulsion system to drive the spacecraft to enter the atmosphere at a steeper flight path angle. It will then enter at a more precise latitude, longitude, and footprint in a nearly uninhabited impact region, generally located in the ocean.

Johnson, Nicholas L.

2006-01-01

208

Independent Orbiter Assessment (IOA): Analysis of the orbital maneuvering system  

NASA Technical Reports Server (NTRS)

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbital Maneuvering System (OMS) hardware are documented. The OMS provides the thrust to perform orbit insertion, orbit circularization, orbit transfer, rendezvous, and deorbit. The OMS is housed in two independent pods located one on each side of the tail and consists of the following subsystems: Helium Pressurization; Propellant Storage and Distribution; Orbital Maneuvering Engine; and Electrical Power Distribution and Control. The IOA analysis process utilized available OMS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluted and analyzed for possible failure modes and effects. Criticality was asigned based upon the severity of the effect for each failure mode.

Prust, C. D.; Paul, D. J.; Burkemper, V. J.

1987-01-01

209

Reduced domestic satellite orbit spacing  

NASA Astrophysics Data System (ADS)

The demand for services provided by communications satellites in geostationary orbit is growing, and problems arise with respect to the required increase in capacity. One approach for providing such an increase involves the employment of more satellites operating at smaller orbital spacings. The present investigation is concerned with the results of technical studies conducted by the Federal Communications Commission (FCC) to determine the feasibility of reducing orbital spacings between U.S. 'domestic fixed satellites' (domsats). Attention is given to details regarding the usable orbital arc, an adjacent satellite interference model, antenna sidelobe patterns, a single entry analysis, a 4/6 GHz aggregate analysis, results for the 4/6 GHz bands, results for the 12/14 GHz bands, data services, voice services, video reception, and high power spot beams.

Sharp, G. L.

210

The orbit of Pluto's satellite  

NASA Technical Reports Server (NTRS)

Nineteen speckle interferometric observations of the Pluto system have been used to improve the determination of the orbital elements for Pluto's satellite. Calibration uncertainties appear to be the dominant source of error, but the observation of a partial occultation of the satellite by Pluto has been used to constrain the orbit solution. The orbital period is found to be in excellent agreement with the rotational period of the planet, reinforcing the belief that the system is completely tidally evolved. The orbital radius and period imply a total mass for the system of 6.8 + or - 0.5 x 10 to the -9th solar masses. Density constraints place an upper limit of 3615 + or - 90 km on the diameter of Pluto, while observations of the first mutual events establish a crude lower limit of about 2800 km.

Tholen, D. J.

1985-01-01

211

How to Orbit the Earth.  

ERIC Educational Resources Information Center

Discusses the geometry, algebra, and logic involved in the solution of a "Mindbenders" problem in "Discover" magazine and applies it to calculations of satellite orbital velocity. Extends the solution of this probe to other applications of falling objects. (JM)

Quimby, Donald J.

1984-01-01

212

Orbital evolution of some Centaurs  

NASA Astrophysics Data System (ADS)

In this work we investigated the dynamical evolution of Centaurs objects 2060 (Chiron), 5145 (Pholus), 7066 (Nessus), 8405 (Asbolus), 10199 (Chariklo), 10370 (Hylonome), and Scattered-Disk object 15874. We have carried out orbital integration of test particles with initial orbits similar to those of these objects. Calculations were produced for +/-600kyr-10Myr starting at epoch and using the implicit single sequence Everhart methods. 12 variational orbits for each of selected Centaurs also have been numerically integrated for +/-200 kyr toward the past and the future. The most probable paths were traced up to +/-1 Myr. The character of orbital elements changes and peculiarities of close approaches to giant planets are discussed.

Kovalenko, Nataliya; Babenko, Yuri; Churyumov, Klim

2002-11-01

213

Orbiting molecular-beam laboratory  

NASA Technical Reports Server (NTRS)

The composition of the atmosphere within the planned orbital envelope of the Space Shuttle and the velocity necessary to maintain a stable orbit within that envelope provide unique conditions for forming a high-purity, moderate energy beam (about 5 eV) of atomic oxygen. At 500 km, for example, atomic oxygen comprises approximately 90% of the atmosphere. Since the mean thermal speed of the ambient atomic oxygen is substantially less than the orbital speed, a high-purity beam can be generated by sweeping through the gas with a series of beam-forming truncated conical shells. Characteristics of the beam, including energy distribution, flux, and purity variation with orbital altitude and methods for lowering the mean energy, are presented. Gas-surface interaction experiments that have been proposed for this laboratory are also discussed.

Outlaw, R. A.; Brock, F. J.

1977-01-01

214

Orbital Maneuvering system design evolution  

NASA Technical Reports Server (NTRS)

Preliminary design considerations and changes made in the baseline space shuttle orbital maneuvering system (OMS) to reduce cost and weight are detailed. The definition of initial subsystem requirements, trade studies, and design approaches are considered. Design features of the engine, its injector, combustion chamber, nozzle extension and bipropellant valve are illustrated and discussed. The current OMS consists of two identical pods that use nitrogen tetroxide (NTO) and monomethylhydrazine (MMH) propellants to provide 1000 ft/sec of delta velocity for a payload of 65,000 pounds. Major systems are pressurant gas storage and control, propellant storage supply and quantity measurement, and the rocket engine, which includes a bipropellant valve, an injector/thrust chamber, and a nozzle. The subsystem provides orbit insertion, circularization, and on orbit and deorbit capability for the shuttle orbiter.

Gibson, C.; Humphries, C.

1985-01-01

215

First Orbits for Five Binaries  

NASA Astrophysics Data System (ADS)

In this paper, new orbital elements are given for five binaries. For all of them—Washington Double Star (WDS) 00469+4339 = HDS 102, WDS 02186+4017 = EGG 2Aa, WDS 05542 - 2909 = FIN 382, WDS 06493- 0216 = FIN 322, and WDS 11495 - 4604 = FIN 366—the orbital elements are calculated for the first time. One of the five binaries, HDS 102, was discovered during the Hipparcos mission, whereas the remaining four were discovered between 1952 and 1965. All measured separations are less than 0farcs3 and most of the measures were done using the interferometric techniques. The orbital periods calculated are between 28 and 109 years. In addition to the orbital elements, the (O - C) residuals in ? and ?, masses, dynamical parallaxes, absolute magnitudes, and ephemerides for the next five years are also given in this paper.

Cvetkovi?, Z.

2008-10-01

216

Lunar orbital mass spectrometer experiment  

NASA Technical Reports Server (NTRS)

The design, development, manufacture, test and calibration of five lunar orbital mass spectrometers with the four associated ground support equipment test sets are discussed. A mass spectrometer was installed in the Apollo 15 and one in the Apollo 16 Scientific Instrument Module within the Service Module. The Apollo 15 mass spectrometer was operated with collection of 38 hours of mass spectra data during lunar orbit and 50 hours of data were collected during transearth coast. The Apollo 16 mass spectrometer was operated with collection of 76 hours of mass spectra data during lunar orbit. However, the Apollo 16 mass spectrometer was ejected into lunar orbit upon malfunction of spacecraft boom system just prior to transearth insection and no transearth coast data was possible.

Lord, W. P.

1971-01-01

217

Two stage to orbit design  

NASA Technical Reports Server (NTRS)

A preliminary design of a two-stage to orbit vehicle was conducted with the requirements to carry a 10,000 pound payload into a 300 mile low-earth orbit using an airbreathing first stage, and to take off and land unassisted on a 15,000 foot runway. The goal of the design analysis was to produce the most efficient vehicle in size and weight which could accomplish the mission requirements. Initial parametric analysis indicated that the weight of the orbiter and the transonic performance of the system were the two parameters that had the largest impact on the design. The resulting system uses a turbofan ramjet powered first stage to propel a scramjet and rocket powered orbiter to the stage point of Mach 6 to 6.5 at an altitude of 90,000 ft.

1991-01-01

218

The Earth and Moon's Orbit  

NSDL National Science Digital Library

The following activities will help you explore how the earth and moon move around the sun. Activity 1: Go to the following activity below and then answer the questions below in your science journal. The Earth s Orbit Activity 1) How many months did it take to get the earth to orbit the sun one time? 2) Describe the motion of the earth and moon as it traveled around the sun? 3) How many hours ...

2009-02-28

219

Orbits in a logarithmic potential  

SciTech Connect

The characteristics of charged particle orbits in the logarithmic electrostatic potential field surrounding a straight conducting wire at a fixed potential are investigated. The equations of motion of an electron in a logarithmic potential are derived, the limiting cases are considered, and the results of numerical integration of the equations of motion are presented along with sketches of a few representative orbits. (C.E.S.)

Hooverman, R.H.

2014-04-15

220

Multimodality imaging of the orbit  

PubMed Central

The role of imaging is well established in the evaluation of orbital diseases. Ultrasonography, Computed tomography and Magnetic resonance imaging are complementary modalities, which allow direct visualization of regional anatomy, accurate localization and help to characterize lesions to make a reliable radiological diagnosis. The purpose of this pictorial essay is to highlight the imaging features of commonly encountered pathologies which involve the orbit. PMID:23599570

Hande, Pradipta C; Talwar, Inder

2012-01-01

221

Orbital servicing of space platforms  

NASA Technical Reports Server (NTRS)

NASA-MSFC is planning systems for the orbital servicing and maintenance of large geosynchronous platforms. The goal is to devise methods to maintain, update, and/or replace the basic spacecraft housekeeping equipment as well as the onboard mission equipment. The planning has passed through the feasibility demonstration level. A hard engineering test unit of such an on-orbit servicing system, complete with control system, is being tested and evaluated by MSFC.

Turner, J. R.; Derocher, W. L., Jr.

1978-01-01

222

Five Planets Orbiting 55 Cancri  

E-print Network

We report 18 years of Doppler shift measurements of a nearby star, 55 Cancri, that exhibit strong evidence for five orbiting planets. The four previously reported planets are strongly confirmed here. A fifth planet is presented, with an apparent orbital period of 260 days, placing it 0.78 AU from the star in the large empty zone between two other planets. The velocity wobble amplitude of 4.9 \\ms implies a minimum planet mass \\msini = 45.7 \\mearthe. The orbital eccentricity is consistent with a circular orbit, but modest eccentricity solutions give similar \\chisq fits. All five planets reside in low eccentricity orbits, four having eccentricities under 0.1. The outermost planet orbits 5.8 AU from the star and has a minimum mass, \\msini = 3.8 \\mjupe, making it more massive than the inner four planets combined. Its orbital distance is the largest for an exoplanet with a well defined orbit. The innermost planet has a semi-major axis of only 0.038 AU and has a minimum mass, \\msinie, of only 10.8 \\mearthe, one of the lowest mass exoplanets known. The five known planets within 6 AU define a {\\em minimum mass protoplanetary nebula} to compare with the classical minimum mass solar nebula. Numerical N-body simulations show this system of five planets to be dynamically stable and show that the planets with periods of 14.65 and 44.3 d are not in a mean-motion resonance. Millimagnitude photometry during 11 years reveals no brightness variations at any of the radial velocity periods, providing support for their interpretation as planetary.

Debra A. Fischer; Geoffrey W. Marcy; R. Paul Butler; Steven S. Vogt; Greg Laughlin; Gregory W. Henry; David Abouav; Kathryn M. G. Peek; Jason T. Wright; John A. Johnson; Chris McCarthy; Howard Isaacson

2007-12-27

223

Orbital Debris Studies at NASA  

NASA Technical Reports Server (NTRS)

Any discussion of expanding the capabilities of Space Surveillance Networks to include tracking and cataloging smaller objects will require a good understanding of orbital debris. In the current U.S. catalog of over 11,000 objects, more than 50% are classified as "debris" to include fragmentation debris, operational debris, liquid metal coolant, and Westford needles. If the catalog is increased to 100,000 objects by lowering the tracked object size threshold, almost all of the additional objects will be orbital debris. The Orbital Debris Program Office has been characterizing the small orbital debris environment through measurements and modeling for many years. This presentation will specifically discuss two different studies conducted at NASA. The first study was done in 1992 and examined the requirements and produced a conceptual design for a Collision Avoidance Network to protect the Space Station Freedom from centimeter sized orbital debris while minimizing maneuvers. The second study was conducted last year and produced NASA s estimate of the orbital population for the years 2015 and 2030 for objects 2 cm and larger.

Stansbery, Gene; Krisko, Paula; Whitlock, Dave

2007-01-01

224

Low Earth orbit communications satellite  

NASA Astrophysics Data System (ADS)

A current thrust in satellite communication systems considers a low-Earth orbiting constellations of satellites for continuous global coverage. Conceptual design studies have been done at the time of this design project by LORAL Aerospace Corporation under the program name GLOBALSTAR and by Motorola under their IRIDIUM program. This design project concentrates on the spacecraft design of the GLOBALSTAR low-Earth orbiting communication system. Overview information on the program was gained through the Federal Communications Commission licensing request. The GLOBALSTAR system consists of 48 operational satellites positioned in a Walker Delta pattern providing global coverage and redundancy. The operational orbit is 1389 km (750 nmi) altitude with eight planes of six satellites each. The orbital planes are spaced 45 deg., and the spacecraft are separated by 60 deg. within the plane. A Delta 2 launch vehicle is used to carry six spacecraft for orbit establishment. Once in orbit, the spacecraft will utilize code-division multiple access (spread spectrum modulation) for digital relay, voice, and radio determination satellite services (RDSS) yielding position determination with accuracy up to 200 meters.

Moroney, D.; Lashbrook, D.; McKibben, B.; Gardener, N.; Rivers, T.; Nottingham, G.; Golden, B.; Barfield, B.; Bruening, J.; Wood, D.

225

Orbital Polarization in Itinerant Magnets  

NASA Astrophysics Data System (ADS)

The correct description of the orbital magnetism is one of the longstanding problems in the density functional theory (DFT). One possible solution is to extend DFT by considering explicit dependence of the exchange-correlation energy on the orbital degrees of freedom. Since the angular momentum operator does not commute with electrostatic potential, it is not an observable except a small atomic region where this potential is nearly spherical. Hence, the orbital magnetism is an atomic property, and we inevitably have to deal with the problem of on-site Coulomb interactions and screening of these interactions in solids.^1 For itinerant systems, this screening can be evaluated in the random-phase approximation (RPA), by considering the strong-coupling limit. Then, the orbital polarization can be computed as the self-energy correction in the static version of the GW method, without any adjustable parameters.^2 This opens a formal way for combining the spin itineracy in the local-spin-density approximation (LSDA) with the atomic orbital magnetism. RPA can be further improved by restoring the spin polarization of LSDA through the local- field corrections. Numerical applications reveal a remarkable improvement for the orbital magnetization and magnetocrystalline anisotropy energies of transition metals and actinide compounds. ^1 I. V. Solovyev et al., Phys. Rev. Lett. 80, 5758 (1998). ^2 I. V. Solovyev, Phys. Rev. Lett. 95, 267205 (2005).

Solovyev, Igor

2007-03-01

226

Low Earth orbit communications satellite  

NASA Technical Reports Server (NTRS)

A current thrust in satellite communication systems considers a low-Earth orbiting constellations of satellites for continuous global coverage. Conceptual design studies have been done at the time of this design project by LORAL Aerospace Corporation under the program name GLOBALSTAR and by Motorola under their IRIDIUM program. This design project concentrates on the spacecraft design of the GLOBALSTAR low-Earth orbiting communication system. Overview information on the program was gained through the Federal Communications Commission licensing request. The GLOBALSTAR system consists of 48 operational satellites positioned in a Walker Delta pattern providing global coverage and redundancy. The operational orbit is 1389 km (750 nmi) altitude with eight planes of six satellites each. The orbital planes are spaced 45 deg., and the spacecraft are separated by 60 deg. within the plane. A Delta 2 launch vehicle is used to carry six spacecraft for orbit establishment. Once in orbit, the spacecraft will utilize code-division multiple access (spread spectrum modulation) for digital relay, voice, and radio determination satellite services (RDSS) yielding position determination with accuracy up to 200 meters.

Moroney, D.; Lashbrook, D.; Mckibben, B.; Gardener, N.; Rivers, T.; Nottingham, G.; Golden, B.; Barfield, B.; Bruening, J.; Wood, D.

1992-01-01

227

Harmonic structure of generic Kerr orbits  

NASA Astrophysics Data System (ADS)

Generic Kerr orbits exhibit intricate three-dimensional motion. We offer a classification scheme for these intricate orbits in terms of periodic orbits. The crucial insight is that for a given effective angular momentum L and angle of inclination ?, there exists a discrete set of orbits that are geometrically n-leaf clovers in a precessing orbital plane. When viewed in the full three dimensions, these orbits are periodic in r-?. Each n-leaf clover is associated with a rational number, 1+qr?=??/?r, that measures the degree of perihelion precession in the precessing orbital plane. The rational number qr? varies monotonically with the orbital energy and with the orbital eccentricity. Since any bound orbit can be approximated as near one of these periodic n-leaf clovers, this special set offers a skeleton that illuminates the structure of all bound Kerr orbits, in or out of the equatorial plane.

Grossman, Rebecca; Levin, Janna; Perez-Giz, Gabe

2012-01-01

228

Space Tourism: Orbital Debris Considerations  

NASA Astrophysics Data System (ADS)

Space activities after a phase of research and development, political competition and national prestige have entered an era of real commercialization. Remote sensing, earth observation, and communication are among the areas in which this growing industry is facing competition and declining government money. A project like International Space Station, which draws from public money, has not only opened a window of real multinational cooperation, but also changed space travel from a mere fantasy into a real world activity. Besides research activities for sending man to moon and Mars and other outer planets, space travel has attracted a considerable attention in recent years in the form of space tourism. Four countries from space fairing nations are actively involved in the development of space tourism. Even, nations which are either in early stages of space technology development or just beginning their space activities, have high ambitions in this area. This is worth noting considering their limited resources. At present, trips to space are available, but limited and expensive. To move beyond this point to generally available trips to orbit and week long stays in LEO, in orbital hotels, some of the required basic transportations, living requirements, and technological developments required for long stay in orbit are already underway. For tourism to develop to a real everyday business, not only the price has to come down to meaningful levels, but also safety considerations should be fully developed to attract travelers' trust. A serious hazard to space activities in general and space tourism in particular is space debris in earth orbit. Orbiting debris are man-made objects left over by space operations, hazardous to space missions. Since the higher density of debris population occurs in low earth orbit, which is also the same orbit of interest to space tourism, a careful attention should be paid to the effect of debris on tourism activities. In this study, after a review of the current work on space tourism and debris situation in low earth orbit suitable orbits for space tourism activities with regard to the presence of orbital debris are discussed.

Mahmoudian, N.; Shajiee, S.; Moghani, T.; Bahrami, M.

2002-01-01

229

Modeling issues in precision orbit determination for Mars orbiter  

NASA Technical Reports Server (NTRS)

This paper examines the accuracy of recent Mars gravity models and the importance of perturbations due to the Mars radiation pressure and the Martian moons, Phobos and Deimos, on the trajectories of Mars orbiters. A linear orbit perturbation theory is used to characterize the patterns of gravity field near resonances for the Viking and Mariner 9 spacecraft. These resonances are shown to have considerable power and their potential for contributing to Mars gravity solutions is emphasized. It is shown that some of the same resonance orders which appear in the Viking orbits, dominate the radial orbit error spectrum for Mars Observer. Results of orbit determination simulations at the Goddard Space Flight Center show that the perturbations caused by the Martian moons and the Mars radiation pressure are larger than 0.1 mm/s, the expected precision of the Mars Observer Doppler tracking data. Tests with the Viking Doppler data indicate that best analysis of these data mandates the inclusion of the Phobos gravitational perturbation in the modeling of Viking spacecraft trajectories.

Lemoine, Frank G.; Rosborough, George W.; Smith, David E.

1990-01-01

230

THE ORBITS OF THE OUTER URANIAN SATELLITES  

SciTech Connect

We report on the numerically integrated orbits for the nine outer Uranian satellites. The orbits are calculated based on fits to the astrometric observations for the period from 1984 to 2006. The results include the state vectors, post-fit residuals, and mean orbital elements. We also assess the accuracy of the orbital fits and discuss the need for future measurements.

Brozovic, M.; Jacobson, R. A. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States)], E-mail: marina.brozovic@jpl.nasa.gov

2009-04-15

231

Mars Orbiter Most Likely Lost  

NSDL National Science Digital Library

In an embarrassing setback to NASA, the Mars Climate Orbiter is believed lost. In the early hours of September 23, the orbiter fired its main engine to go in orbit around Mars and passed behind the planet, losing radio contact as planned. However, due to what was most likely a navigation error, the spacecraft did not resume contact and may have flown too close to the atmosphere and broken apart or burned up. The relatively inexpensive ($125 million) Climate Orbiter was launched in December 1998 to become the first interplanetary weather satellite, studying Martian weather for one Mars year (about two Earth years). It was also to serve as a relay station for five years, relaying information to and from the Mars Polar Lander, due to land on December 3, 1999. NASA, however, insists that the Polar Lander's mission can be accomplished independently and "the science return of that mission won't be affected." The sites listed provide information about Mars Climate Orbiter and its possible loss.

de Nie, Michael Willem.

232

Orbit Evolution in Common Envelopes  

NASA Astrophysics Data System (ADS)

We study how the inclination angle and eccentricity evolve during a common envelope phase. During a common envelope phase, a compact star is swallowed by its giant companion and spirals into a tighter orbit. A close binary results if the compact star releases enough energy to expel the envelope. We investigate possible fossil evidence of the common envelope phase on the inclination angle and the eccentricity. A convective common envelope leads to force component perpendicular to the orbital plane, and thus change the orbital inclination. This makes it harder to uniquely identify the signature of neutron star natal kicks. A common envelope is usually assumed to circularize orbits, but some eccentricity in fact arises both from the spiral-in process itself, and from random forces in the orbital plane. When the envelope is expelled, it might seem that the binary system would preserve whatever eccentricity had been established at the final stage of the inspiral. But tidal dissipation by the residual envelope can reduce the eccentricity. The final eccentricity depends on which of these effects wins or how they balance each other. We discuss applications and observational tests of these predictions.

Luan, Jing; Phinney, E. S.

2011-09-01

233

First Spacecraft Orbit of Mercury  

NASA Astrophysics Data System (ADS)

After a 7.9-billion-kilometer flight since its launch on 3 August 2004—which included flybys of Earth, Venus, and Mercury—NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered a planned, highly elliptical orbit around the closest planet to our Sun on 17 March. Engineers in the mission operations center at the Johns Hopkins University Applied Physics Laboratory (JHU/APL) in Laurel, Md., which manages the mission for NASA, received radiometric signals indicating a successful orbit insertion at 9:10 P.M. local time. "Tonight we will have orbited the fifth planet in the solar system. This is a major accomplishment," Ed Weiler, NASA assistant administrator for the Science Mission Directorate, said at a 17 March public forum at JHU/APL, noting that spacecraft have previously entered orbit around several other planets. "You only go into orbit for the first time around Mercury once in human history, and that is what was accomplished tonight."

Showstack, Randy

2011-03-01

234

Orbital-corrected orbital-free density functional theory Baojing Zhou and Yan Alexander Wanga  

E-print Network

Orbital-corrected orbital-free density functional theory Baojing Zhou and Yan Alexander Wanga of density functional theory DFT , namely orbital-corrected orbital-free OO DFT, has been developed systems. Our work provides a new impetus to further improve orbital-free DFT method and presents a robust

Wang, Yan Alexander

235

CONSTRUCTION OF STABLE PERIODIC ORBITS FOR THE SPIN--ORBIT PROBLEM OF  

E-print Network

CONSTRUCTION OF STABLE PERIODIC ORBITS FOR THE SPIN--ORBIT PROBLEM OF CELESTIAL MECHANICS--mail: luigi@matrm3.mat.uniroma3.it ABSTRACT. Birkhoff periodic orbits associated to spin--orbit resonances of such orbits with particular attention to ``effective estimates'' on the size of the perturbative parameters

236

Orbital extension of trigeminal schwannoma  

PubMed Central

Schwannomas, also known as neurilemmomas, are benign peripheral nerve sheath tumors. Trigeminal schwannomas are rare intracranial tumors. Here, we report a 35-year-old female presenting with an axial proptosis of right eyeball with right-sided III, IV and VI cranial nerve palsy. Her best corrected visual acuity in the right eye was perception of light absent and in the left eye was 20/20. MRI scan revealed a large right-sided heterogeneous, extra-axial middle cranial fossa mass that extended to the intraconal space of right orbit. A diagnosis of intracranial trigeminal nerve schwannoma with right orbital extension was made. Successful surgical excision of the mass with preservation of the surrounding tissues and orbital exenteration was done. Post-operative period was uneventful. PMID:25552864

Ghosh, Shantanu; Das, Debabrata; Varshney, Rahul; Nandy, Sumit

2015-01-01

237

Orbital extension of trigeminal schwannoma.  

PubMed

Schwannomas, also known as neurilemmomas, are benign peripheral nerve sheath tumors. Trigeminal schwannomas are rare intracranial tumors. Here, we report a 35-year-old female presenting with an axial proptosis of right eyeball with right-sided III, IV and VI cranial nerve palsy. Her best corrected visual acuity in the right eye was perception of light absent and in the left eye was 20/20. MRI scan revealed a large right-sided heterogeneous, extra-axial middle cranial fossa mass that extended to the intraconal space of right orbit. A diagnosis of intracranial trigeminal nerve schwannoma with right orbital extension was made. Successful surgical excision of the mass with preservation of the surrounding tissues and orbital exenteration was done. Post-operative period was uneventful. PMID:25552864

Ghosh, Shantanu; Das, Debabrata; Varshney, Rahul; Nandy, Sumit

2015-01-01

238

The Mariner Mars 1971 orbiter.  

NASA Technical Reports Server (NTRS)

The Mariner Mars 1971 (MM '71) orbiter spacecraft, launched toward Mars in the spring of 1971, was designed to offer the first opportunity for sustained observations in the near vicinity of another planet of our solar system. The MM '71 spacecraft, like its predecessors, is fully attitude stabilized about three axes, using the sun and Canopus as references, an orientation which allows use of photovoltaic solar panels for primary power and permits two-way communication to the earth through a high-gain directional antenna. Midcourse and orbit insertion maneuvers use the sun-Canopus orientation as a reference direction for initiating commanded turns. Scientific instruments employed during Mars orbital operations are mounted on a two-degree-of-freedom platform controlled by commands from the central computer and sequencer. Science measurements to be obtained by the MM '71 spacecraft include television visual imaging, infrared radiometry, infrared spectroscopy, ultraviolet spectroscopy, S-band radio occultation, and celestial mechanics.

Scull, J. R.

1972-01-01

239

Comprehensive management of orbital fractures.  

PubMed

Orbital fractures are some of the more challenging injuries faced by the plastic surgeon. As such a prominent facial feature, even the most minor asymmetries following trauma can be distressing to the patient. In treating these patients, there are certain crucial aspects of both diagnosis and management that are critical to obtaining an optimal result. These include a careful preparative eye examination focusing on extraocular motility and any evidence of optic nerve compression. Candidates for surgery must be carefully selected based on firm indications such as a large orbital floor defect (>1 cm2), early enophthalmos, significant hypoglobus, or persistent diplopia in the primary field of gaze. Reconstruction should focus on anatomical restitution of the floor, taking great care to place the implant along the correct superior inclination of the orbit. PMID:18090729

Cole, Patrick; Boyd, Vincent; Banerji, Soumo; Hollier, Larry H

2007-12-01

240

The Challenge of Orbital Debris  

NASA Technical Reports Server (NTRS)

Since the dawn of the Space Age more than 50 years ago, humans have been launching objects into the space environment faster than they have been removed by active means or natural decay. This has led to a proliferation of debris -- derelict satellites, discarded rocket upper stages, and pieces from satellite breakups -- in Earth orbit, especially in well-used orbital regimes. This talk will summarize the current knowledge of the debris environment and describe plans to address the challenges orbital debris raises for the future usability of near-Earth space. The talk will be structured around 4 categories: Measurements, Modeling, Shielding, and Mitigation. This will include discussions of the long-term prognosis of debris growth (i.e., the "Kessler Syndrome") as well as plans for active debris removal.

Matney, Mark

2012-01-01

241

Apollo 15 orbital science summary.  

NASA Technical Reports Server (NTRS)

In this paper, summary results of the Apollo 15 orbital science payload are given, and some quick-look results of Apollo 16 are discussed. Geochemical instruments, consisting of gamma-ray, X-ray, and alpha particle spectrometers, have provided a chemical map of the lunar surface flown over by Apollo 15. The Laser Altimeter and frontside gravity data have shown some unexpected results with regard to the lunar shape, and provided new basis for understanding lunar mascons. A magnetometer, aboard the small subsatellite, has located magnetic anomalies principally on the lunar farside, and has shown that the small lunar magnetic field is smoother on the frontside than on the back. The mass spectrometer, in orbit aboard the Command and Service Modules, has measured unexpectedly large populations of molecules at orbital altitude (110 km), mostly due to spacecraft contamination. Two major camera systems have provided the first systematic metric quality photography and concurrent high resolution stereo coverage of the lunar surface.

Esenwein, G. F.; Roberson, F. I.

1972-01-01

242

Bound orbits and gravitational theory  

NASA Astrophysics Data System (ADS)

It can be easily shown that bound orbits around a static source can only exist in four dimensions for any force driven by the Laplace equation. This is true not only for Maxwell’s electromagnetism and Newton’s gravity, but for Einstein’s theory of gravitation as well. In contrast to Maxwell’s electrodynamics and Newton’s gravity, general relativity has a natural and remarkable generalization in higher dimensions in Lovelock gravity. However, it is not Laplace driven and hence admits bound orbits around a static black hole in all even D=2N+2 dimensions, where N is the degree of the Lovelock polynomial action. This is as general a result as Bertrand’s theorem of classical mechanics, in which the existence of closed orbits uniquely singles out the inverse square law for a long-range central force.

Dadhich, Naresh; Ghosh, Sushant G.; Jhingan, Sanjay

2013-12-01

243

Short-Arc Correlation and Initial Orbit Determination For Space-Based Observations  

NASA Astrophysics Data System (ADS)

Initial orbit determination (IOD) of space debris is an important segment of space situational awareness and is often coupled with the problem of track correlation, since in order to determine the orbit of an observed object, multiple observations must be combined. It is generally uncertain, however, whether two arbitrary tracks are of the same object. Recently, Fujimoto and Scheeres have proposed a novel and rigorous track correlation and IOD technique where each observation is assigned an “admissible region” in state space based on some physical constraints. The relationship of two observations is then determined by finding whether these regions intersect via Bayes’ rule. In this paper, we propose a new application of this method to space-based observations. Preliminary results show robustness to classically singular geometries, such as GEO-on-GEO observations. Admissible regions were first proposed by Milani et al. for heliocentric orbits, and Tommei et al. expanded this concept to Earth orbiting objects. Maruskin et al. was first to introduce the concept of intersecting multiple admissible regions to correlate tracks and obtain an initial orbit estimate, albeit the correlation was conducted in 2-dimensional subspaces of the state space. Fujimoto and Scheeres fully developed ways of characterizing intersections of admissible regions in the full 6-dimensional state space. They showed through topological arguments that a positive correlation also simultaneously provides an initial orbit estimate. A method of linearly mapping admissible regions to the state space was introduced in order to improve computational turn-around, and was validated with a series of numerical tests. For space-based observations, the observation location vector, previously assumed to be Earth-fixed, is now allowed to propagate under two-body dynamics. Several technical challenges arise when we make this change. First, the admissible region spans over a larger region in the state space, making the correlation process more computationally intensive. Second, a modification must be made to the correlation process as the observer's state is always a valid solution. That is, any admissible region map from a space-based observation will intersect with any other map from the same observing satellite at the observing satellite's state. This problem is circumvented by automatically refining the state space discretization and throwing away solutions near the observing satellite's state. Numerical examples for several observation scenarios are discussed in this paper, including LEO-on-GEO and GEO-on-GEO observations. The LEO satellite is in a circular sun-synchronous orbit at 630 km altitude, much like the SBSS System. For existing IOD techniques there are known observation geometries that experience singularities such as the GEO-on-GEO case. Preliminary results show that our method does not suffer such singularities for the GEO-on-GEO observation scenario. This outcome is most likely due to the fact that we are combining 2 observations for a total of 8 observable variables, instead of the minimum 6, to obtain an initial orbit estimate. We believe this additional information removes the singularity from the problem.

Fujimoto, K.; Scheeres, D.

2011-09-01

244

Orbital Polarization in Itinerant Magnets  

NASA Astrophysics Data System (ADS)

We propose a parameter-free scheme of calculation of the orbital polarization (OP) in metals, which starts with the strong-coupling limit for the screened Coulomb interactions in the random-phase approximation (RPA). For itinerant magnets, RPA can be further improved by restoring the spin polarization of the local-spin-density approximation through the local-field corrections. The OP is then computed as the self-energy correction in the static GW method, which systematically improves the orbital magnetization and the magnetic anisotropy energies in transition-metal and actinide compounds.

Solovyev, I. V.

2005-12-01

245

Orbital polarization in itinerant magnets.  

PubMed

We propose a parameter-free scheme of calculation of the orbital polarization (OP) in metals, which starts with the strong-coupling limit for the screened Coulomb interactions in the random-phase approximation (RPA). For itinerant magnets, RPA can be further improved by restoring the spin polarization of the local-spin-density approximation through the local-field corrections. The OP is then computed as the self-energy correction in the static GW method, which systematically improves the orbital magnetization and the magnetic anisotropy energies in transition-metal and actinide compounds. PMID:16486395

Solovyev, I V

2005-12-31

246

Orbits of swimmers around obstacles  

E-print Network

We present a two dimensional model of hydrodynamic interaction between a circular swimmer and a circular post at low Reynolds number, using a point singularity description of the swimming activity. We derive a nonlinear dynamical system fully describing the motion and discuss the generic features of the phase portrait and typical trajectories for a variety of squirmer modes. Contractile swimmers exhibit stable bound orbits arising from the contrasting nature of monopolar and dipolar squirmer modes, which are robust with respect to swimmer size and the inclusion of higher squirmer modes. The behaviour of extensile swimmers is related through time reversal and their orbits are unstable, in qualitative agreement with experimental observations.

Dario Papavassiliou; Gareth P Alexander

2014-07-04

247

Nodular Fasciitis of the Orbit.  

PubMed

A 13-month-old boy was presented with new onset proptosis of the right eye. CT scan and MRI showed an enhancing mass in the right superior orbit with local bone remodeling and erosion. A craniotomy was performed for biopsy and sub-total resection. Histopathology and immunohistochemistry confirmed the lesion to be nodular fasciitis. Nodular fasciitis lesions are classically found in the anterior ocular adnexa, especially in pediatric patients. This is the first reported case of nodular fasciitis arising in the posterior orbit of a child younger than 16. PMID:25393905

Compton, Christopher J; Clark, Jeremy D; Thompson, Matthew P; Lee, Hui Bae H; Nunery, William R

2014-11-12

248

MUSES-A orbital design  

NASA Astrophysics Data System (ADS)

A multiple lunar swingby applied for MUSES-A in 1990 has spurred a development of orbital design tools such as the B-plane Interactive Targeter (BITAR) and the Database Inheritable Targeter (DITAR). The BITAR enables a multiple B-plane targeting on a graphic display screen, while the DITAR is capable of targeting to a reference database given a priori. Although both tools function by themselves, a mutual data exchange accelerates efficiency. To accommodate probabilistic quantities associated with an orbital determination as well as a thruster firing, an operational flow management system is considered.

Yokota, Hiroki; Kawaguchi, Jun'ichiro; Uesugi, Kuninori; Ishii, Shuichi

249

Orbiter electrical equipment utilization baseline  

NASA Technical Reports Server (NTRS)

The baseline for utilization of Orbiter electrical equipment in both electrical and Environmental Control and Life Support System (ECLSS) thermal analyses is established. It is a composite catalog of Space Shuttle equipment, as defined in the Shuttle Operational Data Book. The major functions and expected usage of each component type are described. Functional descriptions are designed to provide a fundamental understanding of the Orbiter electrical equipment, to insure correlation of equipment usage within nominal analyses, and to aid analysts in the formulation of off-nominal, contingency analyses.

1980-01-01

250

Orbit precession and orbital period shortening in close binary systems  

E-print Network

We describe phenomenologically well-known effects in close binary systems. The uniform precession of an elliptical orbit is described by the adding of an inverse cube to an inverse square of the distance. If the precession is small, then the inverse cube contribution is small as compared to the one of inverse square. At some value of the distance these contributions become equal.

A. V. Serghienko

2010-05-21

251

Optimization of space orbits design for Earth orbiting missions  

NASA Astrophysics Data System (ADS)

In Earth orbiting space missions, the orbit selection dictates the mission parameters like the ground resolution, the area coverage, and the frequency of coverage parameters. To achieve desired mission parameters, usually Earth regions of interest are identified and the spacecraft is maneuvered continuously to visit only these regions. This method is expensive, it requires a propulsion system onboard the spacecraft, working throughout the mission lifetime. It also requires a longer time to cover all the regions of interest, due to the very weak thrust forces compared to that of the Earth's gravitational field. This paper presents a methodology to design natural orbits, in which the regions of interest are visited without the use of propulsion systems, depending only on the gravitational forces. The problem is formulated as an optimization problem. A genetic algorithm along with a second order gradient method is implemented for optimization. The design process takes into consideration the gravitational second zonal harmonic, and hence allows for the design of repeated Sun-synchronous orbits. The field of view of the payload is also taken into consideration in the optimization process. Numerical results are presented that demonstrates the efficiency of the proposed method.

Abdelkhalik, Ossama; Gad, Ahmed

2011-04-01

252

Orbital dynamics in galaxy mergers  

NASA Astrophysics Data System (ADS)

In the favored vacuum energy + cold dark matter (ACDM) cosmology, galaxies form through a hierarchical merging process. Mergers between comparable-mass sys tems are qualitatively different from the ongoing accretion of small objects by much larger ones, in that they can radically transform the nature of the merging objects, e.g. through violent relaxation of the stars and dark matter, triggered starbursts, and quasar activity. This thesis covers two phenomena unique to major galaxy mergers: the formation of supermassive black hole (SMBH) binary and triple systems, and the transformation of the stellar orbit structure through violent relaxation, triggered gas inflow, and star formation. In a major merger, the SMBHs can spiral in and form a bound binary in less than a Hubble time. If the binary lifetime exceeds the typical time between mergers, then triple black hole (BH) systems may form. We study the statistics of close triple-SMBH encounters in galactic nuclei by computing a series of three-body orbits with physically-motivated initial conditions appropriate for giant elliptical galaxies. Our simulations include a smooth background potential consisting of a stellar bulge plus a dark matter halo, drag forces due to gravitational radiation and dynamical friction on the stars and dark matter, and a simple model of the time evolution of the inner density profile under heating and mass ejection by the SMBHs. We find that the binary pair coalesces as a result of repeated close encounters in ~85% of our runs. In about 40% of the runs the lightest BH is left wandering through the galactic halo or escapes the galaxy altogether. The triple systems typically scour out cores with mass deficits ~1-2 times their total mass. The high coalescence rate and prevalence of very high-eccentricity orbits could provide interesting signals for the future Laser Interferometer Space Antenna (LISA). Our study of remnant orbit structure involved 42 disk-disk mergers at various gas fractions, and 10 re-mergers of the 40% gas remnants. All simulations were run using a version of GADGET-2 [173] that included subresolution models of radiative cooling, star formation, and supernova and AGN feedback. The potential was frozen at the last snapshot of each simulation and the orbits of ~50,000 randomly chosen stars were integrated for ~100 dynamical times, and classified based on their Fourier spectra using the algorithm of [30]. The 40% gas remnants were found to be dominated by minor-axis tube orbits in their inner regions, whereas box orbits were the dominant orbit family in the inner parts of the dissipationless disk-disk and remnant-remnant systems. The phase space available to minor-axis tube orbits in even the 5% gas remnants was much larger than that in the dissipationless remnants, but the 5% gas remnants are not fast rotators because these orbits tend to be isotropically distributed at low gas fractions. Some of the remnants show significant minor axis rotation, due to large orientation twists in their outer parts (in the 40% gas remnants) and asymmetrically rotating major-axis tube orbits throughout the remnants (in the re-mergers).

Hoffman, Loren

253

Precision orbit computations for Starlette  

NASA Technical Reports Server (NTRS)

The Starlette satellite, launched in February 1975 by the French Centre National d'Etudes Spatiales, was designed to minimize the effects of nongravitational forces and to obtain the highest possible accuracy for laser range measurements. Analyses of the first four months of global laser tracking data confirmed the stability of the orbit and the precision to which the satellite's position is established.

Marsh, J. G.; Williamson, R. G.

1976-01-01

254

Orbital Stability of Dirac Solitons  

NASA Astrophysics Data System (ADS)

We prove H 1 orbital stability of Dirac solitons in the integrable massive Thirring model by working with an additional conserved quantity which complements Hamiltonian, momentum and charge functionals of the general nonlinear Dirac equations. We also derive a global bound on the H 1 norm of the L 2-small solutions of the massive Thirring model.

Pelinovsky, Dmitry E.; Shimabukuro, Yusuke

2014-01-01

255

Autonomous perturbations of LISA orbits  

NASA Astrophysics Data System (ADS)

We investigate autonomous perturbations on the orbits of LISA, namely the effects produced by gravitational fields that can be expressed only in terms of the position, but not of time in the Hill frame. This first step in the study of the LISA orbits has been the subject of recent papers which implement analytical techniques based on a 'post-epicyclic' approximation in the Hill frame to find optimal unperturbed orbits. The natural step forward is to analyze the perturbations to purely Keplerian orbits. In this work, a particular emphasis is put on the tidal field of the Earth assumed to be stationary in the Hill frame. Other relevant classes of autonomous perturbations are those given by the corrections to the solar field responsible for a slow precession and a global stationary field, associated with sources such as the interplanetary dust or a local dark matter component. The inclusion of simple linear contributions in the expansion of these fields produces secular solutions that can be compared with the measurements and possibly used to evaluate some morphological property of the perturbing components.

Pucacco, G.; Bassan, M.; Visco, M.

2010-12-01

256

Of Orbits, Conics, and Grammar  

Microsoft Academic Search

In the half-dozen or so years leading up to the publication of the Principia, Isaac Newton observed the comets of 1680 and 1682 and wrestled with the extent to which his law of gravitation could be applied. In time, he would see the connections between the four possible orbits of a satellite (circular, elliptical, parabolic, and hyperbolic) and the four

Hugh Henderson

2005-01-01

257

Gravitational Orbits and Space Flight  

NSDL National Science Digital Library

These lecture notes discuss Newton's theories of dynamics and gravity. The various kinds of possible orbits are described in this lecture. The evolution of space technology such as rockets, the Space Shuttle, dozens of robot spacecraft, and the human space program are also discussed.

O'Connell, Robert W.

2011-02-22

258

What Shape is Earth's Orbit?  

NSDL National Science Digital Library

This is an activity about the shape of the Earth’s orbit. Learners will first use elements of the orbit of Earth and Pluto and an apparatus using string, a pencil, and pushpins to accurately draw an ellipse, showing the nearly circular shape of the orbits of Earth and Pluto. They then measure real images of the Sun in each season, determining the apparent size of the Sun to see if it changes throughout the year. By determining the apparent size of each Sun image and by seeing the shape of Earth's orbit, learners will confront the misconception that seasons are caused by changing distance of the Earth from the Sun. Finally, learners reflect on the results of the Sun-Earth Survey, which is Activity 2 in this set. This is Activity 4 in the Great Explorations in Math and Science (GEMS) guide titled Real Reasons for Seasons: Sun-Earth Connections. The resource guide is available for purchase from the Lawrence Hall of Science. This activity recommends use of an overhead projector.

2013-02-14

259

Viking orbiter stereo imaging catalog  

NASA Technical Reports Server (NTRS)

The extremely long mission of the two Viking Orbiter spacecraft produced a wealth of photos of surface features. Many of these photos can be used to form stereo images allowing the student of Mars to examine a subject in three dimensional. This catalog is a technical guide to the use of stereo coverage within the complex Viking imaging data set.

Blasius, K. R.; Vertrone, A. V.; Lewis, B. H.; Martin, M. D.

1982-01-01

260

A Mars orbiter mission design  

NASA Astrophysics Data System (ADS)

A preliminary study of a new orbiter mission to Mars using an earth gravity assist is presented. The trajectory resulting from this study has been evaluated utilizing Everhart's (1985) integrator RADAU. The mission sequences are described and compared to other proposed mission designs and some mission opportunities for the years 1997 to 2014 are discussed.

Castronuovo, Marco M.

1992-08-01

261

Launching Social Studies into Orbit.  

ERIC Educational Resources Information Center

As a social studies educator, Christa McAuliffe was delighted that a "non-science teacher" was chosen to become the first teacher to orbit the earth. Her thoughts concerning the NASA space flight and its meaning for the social studies are discussed. (RM)

Stone, Kirk

1986-01-01

262

Orbits Within Spherical Galaxies Model  

NSDL National Science Digital Library

The Orbits Within Spherical Galaxies model displays the two-dimensional trajectories of particles (stars) within a galaxy having a spherically symmetric mass distribution that heuristically approximates the distributions found in galaxies and bulges. The model uses a mass density proposed by Walter Dehnen to describe spatial distributions that vary as râ»â´ and râ»g in galactic envelopes and cores where g is an adjustable power-law parameter. Units are chosen such that a typical galaxy has total mass M=1 and that the gravitational constant G=1. The Orbits Within Spherical Galaxies model is a supplemental simulation for the article "Radial motion in a central potential for singular mass densities" by Ulrich Zürcher and Miron Kaufman in the American Journal of Physics 79(5), 521-526 (2011) and has been approved by the authors and the American Journal of Physics (AJP) editor. The simulation was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_mech_orbits_OrbitsWithinSphericalGalaxies.jar file will run the program if Java is installed.

Christian, Wolfgang

2011-01-12

263

Getting a Crew into Orbit  

ERIC Educational Resources Information Center

Despite the temporary setback in our country's crewed space exploration program, there will continue to be missions requiring crews to orbit Earth and beyond. Under the NASA Authorization Act of 2010, NASA should have its own heavy launch rocket and crew vehicle developed by 2016. Private companies will continue to explore space, as well. At the…

Riddle, Bob

2011-01-01

264

d Orbitals in an Octahedral Ligand Field  

NSDL National Science Digital Library

Here is a page that shows the d orbitals in an axis set. Running the mouse over an orbital reveals the "name" of that orbital. This is good practice for helping students link the name of an orbital to the orientation. This page is linked to an interactive 3-dimensional applet, similar to the one above, that shows the d orbitals in an octahedral ligand field. The user may also click on the name of any one of the d orbitals to obtain a larger 3-dimensional image. The images are rotatable and scalable.

265

Density matrix method for orbital localization  

PubMed Central

A method is presented for localizing molecular orbitals, based on diagonalizing subunits of the density matrix. First, nonbonding orbitals are found by diagonalizing the monatomic subunits; then, diatomic ? or ? bonding and antibonding orbitals are obtained from the diatomic subunits for all bonded pairs of atoms; finally, the delocalized ?-orbitals for particular chromophores are found by projecting the first set out of the self-consistent field (SCF) Hamiltonian. The results show good general agreement with other localization methods, with advantages in the ability to display group orbitals in complex molecules which most closely resemble the SCF orbitals for simple prototypes. PMID:16592668

Caldwell, Dennis; Redington, Patrick; Eyring, Henry

1979-01-01

266

Thermal properties of comet 67P derived from Rosetta/VIRTIS, and orbital observations of Philae landing site  

NASA Astrophysics Data System (ADS)

The Rosetta spacecraft has reached its final target, comet 67P/Churyumov-Gerasimenko, in early August 2014. The VIRTIS imaging spectrometer onboard the Rosetta orbiter has intensively observed both the nucleus and the coma environment in the 0.25-5 microns wavelength range. Nucleus observations are performed with both channels: VIRTIS-M for spectral mapping and VIRTIS-H for high spectral resolution. Dayside surface temperatures in various illumination conditions can be retrieved from the long wavelength range. This allows us to infer local thermal properties. The very irregular shape of 67P results in unusual patterns in the heating / cooling regime of the object, e.g. sudden transitions from day to night. We will present thermal analyses of observations performed during the first mapping phase of the pre-landing activity (August 2014), with a focus on thermo-physical modeling of comet 67P on both regional and local scales, and a special emphasis on the expected landing site. These observations document the state of the comet surface at a time of large heliocentric distance and low activity. The authors acknowledge funding from CNES, ASI, and DLR, the French, Italian and German Space Agencies. Support from the Rosetta and VIRTIS science, instrument, and operation teams is gratefully acknowledged.

Drossart, Pierre; Leyrat, C.; Erard, S.; Capria, M. T.; Capaccioni, F.; Filacchione, G.; Tosi, F.; De Sanctis, M. C.; Arnold, G.; Markus, K.; Bockelée-Morvan, D.; Schmitt, B.; Formisano, M.; Kuehrt, E.

2014-11-01

267

Indirect Orbital Floor Fractures: A Meta-Analysis  

PubMed Central

Orbit fractures are common in the context of orbital trauma. Fractures of the orbital floor without orbital rim involvement are known as indirect orbital floor fractures, pure internal floor fractures, and orbital blowout fractures. In this paper, we have reported a meta-analysis of orbital floor fractures focusing on indications and timing of surgical repair, outcomes, and complications. PMID:20616920

Gonzalez, Mithra O.; Durairaj, Vikram D.

2010-01-01

268

Orbits and Interiors of Planets  

NASA Astrophysics Data System (ADS)

The focus of this thesis is a collection of problems of timely interest in orbital dynamics and interior structure of planetary bodies. The first three chapters are dedicated to understanding the interior structure of close-in, gaseous extrasolar planets (hot Jupiters). In order to resolve a long-standing problem of anomalously large hot Jupiter radii, we proposed a novel magnetohydrodynamic mechanism responsible for inflation. The mechanism relies on the electro-magnetic interactions between fast atmospheric flows and the planetary magnetic field in a thermally ionized atmosphere, to induce electrical currents that flow throughout the planet. The resulting Ohmic dissipation acts to maintain the interior entropies, and by extension the radii of hot Jupiters at an enhanced level. Using self-consistent calculations of thermal evolution of hot Jupiters under Ohmic dissipation, we demonstrated a clear tendency towards inflated radii for effective temperatures that give rise to significant ionization of K and Na in the atmosphere, a trend fully consistent with the observational data. Furthermore, we found that in absence of massive cores, low-mass hot Jupiters can over-flow their Roche-lobes and evaporate on Gyr time-scales, possibly leaving behind small rocky cores. Chapters four through six focus on the improvement and implications of a model for orbital evolution of the solar system, driven by dynamical instability (termed the "Nice" model). Hydrodynamical studies of the orbital evolution of planets embedded in protoplanetary disks suggest that giant planets have a tendency to assemble into multi-resonant configurations. Following this argument, we used analytical methods as well as self-consistent numerical N-body simulations to identify fully-resonant primordial states of the outer solar system, whose dynamical evolutions give rise to orbital architectures that resemble the current solar system. We found a total of only eight such initial conditions, providing independent constraints for the solar system's birth environment. Next, we addressed a significant drawback of the original Nice model, namely its inability to create the physically unique, cold classical population of the Kuiper Belt. Specifically, we showed that a locally-formed cold belt can survive the transient instability, and its relatively calm dynamical structure can be reproduced. The last four chapters of this thesis address various aspects and consequences of dynamical relaxation of planetary orbits through dissipative effects as well as the formation of planets in binary stellar systems. Using octopole-order secular perturbation theory, we demonstrated that in multi-planet systems, tidal dissipation often drives orbits onto dynamical "fixed points," characterized by apsidal alignment and lack of periodic variations in eccentricities. We applied this formalism towards investigating the possibility that the large orbital eccentricity of the transiting Neptune-mass planet Gliese 436b is maintained in the face of tidal dissipation by a second planet in the system and computed a locus of possible orbits for the putative perturber. Following up along similar lines, we used various permutations of secular theory to show that when applied specifically to close-in low-mass planetary systems, various terms in the perturbation equations become separable, and the true masses of the planets can be solved for algebraically. In practice, this means that precise knowledge of the system's orbital state can resolve the sin( i) degeneracy inherent to non-transiting planets. Subsequently, we investigated the onset of chaotic motion in dissipative planetary systems. We worked in the context of classical secular perturbation theory, and showed that planetary systems approach chaos via the so-called period-doubling route. Furthermore, we demonstrated that chaotic strange attractors can exist in mildly damped systems, such as photo-evaporating nebulae that host multiple planets. Finally, we considered planetary formation in highly inclined binary systems,

Batygin, Konstantin

2012-05-01

269

An analysis of thrust of a realistic solar sail with focus on a flight validation mission in a geocentric orbit  

NASA Astrophysics Data System (ADS)

Several scientifically important space flight missions have been identified that, at this time, can only be practically achieved using a solar sail propulsion system. These missions take advantage of the potentially continuous force on the sail, provided by solar radiation, to produce significant changes in the spacecraft's velocity, in both magnitude and/or direction, without the need for carrying the enormous amount of fuel that conventional propulsion systems would require to provide the same performance. However, to provide thrust levels that would support these missions requires solar sail areas in the (tens of) thousands of square meter sizes. To realize this, many technical areas must be developed further and demonstrated in space before solar sails will be accepted as a viable space mission propulsion system. One of these areas concerns understanding the propulsion performance of a realistic solar sail well enough for mission planning. Without this understanding, solar sail orbits could not be predicted well enough to meet defined mission requirements, such as rendezvous or station-keeping, and solar sail orbit optimization, such as minimizing flight time, could be close to impossible. In most mission studies, either an "ideal" sail's performance is used for mission planning, or some top-level assumptions of certain nonideal sail characteristics are incorporated to give a slightly better estimate of the sail performance. This paper identifies the major sources of solar sail thrust performance uncertainty, and analyzes the most significant ones to provide a more comprehensive understanding of thrust generation by a "realistic" solar sail. With this understanding, mission planners will be able to more confidently and accurately estimate the capabilities of such a system. The first solar sail mission will likely be a system validation mission, using a relatively small sail in a geocentric (Earth-centered) orbit. The author has been involved in conceptual design of such missions, and through this became aware of the current status in solar sail system development, and the need for a better understanding of the thrust performance of a "realistic" solar sail. Such a validation mission is significantly different than most of the "operational" science missions envisioned to utilize a solar sail propulsion system. These future missions will likely use very large, very light sails in heliocentric orbits far away from major gravity fields like planets, have very long mission lifetimes (years), and will conduct relatively minor and slow orbital and attitude control maneuvers. Nonetheless, most of the capabilities of later systems can be gleaned from a small geocentric validation mission. This paper is a significant step toward understanding the thrust characteristics and performance of a realistic solar sail, and provides insight to the methods by which this understanding can be corroborated by a solar sail validation mission.

Campbell, Bruce A.

270

Kepler's Orbit - Duration: 0:31.  

NASA Video Gallery

Kepler does not orbit the Earth, rather it orbits the Sun in concert with the Earth, slowly drifting away from Earth. Every 61 Earth years, Kepler and Earth will pass by each other. Throughout the ...

271

Rational orbits around charged black holes  

SciTech Connect

We show that all eccentric timelike orbits in Reissner-Nordstroem spacetime can be classified using a taxonomy that draws upon an isomorphism between periodic orbits and the set of rational numbers. By virtue of the fact that the rationals are dense, the taxonomy can be used to approximate aperiodic orbits with periodic orbits. This may help reduce computational overhead for calculations in gravitational wave astronomy. Our dynamical systems approach enables us to study orbits for both charged and uncharged particles in spite of the fact that charged particle orbits around a charged black hole do not admit a simple one-dimensional effective potential description. Finally, we show that comparing periodic orbits in the Reissner-Nordstroem and Schwarzschild geometries enables us to distinguish charged and uncharged spacetimes by looking only at the orbital dynamics.

Misra, Vedant [Physics Department, Columbia University, New York, New York 10027 (United States); Levin, Janna [Department of Physics and Astronomy, Barnard College of Columbia University, 3009 Broadway, New York, New York 10027 (United States); Institute for Strings, Cosmology and Astroparticle Physics, Columbia University, New York, New York 10027 (United States)

2010-10-15

272

Two designs for an orbital transfer vehicle  

NASA Technical Reports Server (NTRS)

The Orbital Transfer Vehicle (OTV) and systems were researched in the following areas: avionics, crew systems, electrical power systems, environmental control/life support systems, navigation and orbital maneuvers, propulsion systems, reaction control systems (RCS), servicing systems, and structures.

Davis, Richard; Duquette, Miles; Fredrick, Rebecca; Schumacher, Daniel; Somers, Schaeffer; Stafira, Stanley; Williams, James; Zelinka, Mark

1988-01-01

273

Boston University Physics Applets: Orbits and Energy  

NSDL National Science Digital Library

This web page is an interactive physics tutorial relating to orbits. The user can set the initial velocity of an orbiting mass and observe the resulting trajectory. The animations illustrate how initial velocity affects the object's orbital path and can result in collision or a break from orbit. Graphs of kinetic energy and gravitational potential energy accompany the animation. This item is part of a collection of simulation-based activities developed for students of introductory physics.

Duffy, Andrew

2008-08-22

274

SILEX in-orbit performances  

NASA Astrophysics Data System (ADS)

PASTEL embarked on-board SPOT4, French LEO earth observation satellite, and OPALE mounted on-board ARTEMIS, European GEO telecommunication satellite are the key components of SILEX (Semi-conductor Inter-satellite Link Experiment) system. Launched in March 1998, PASTEL terminal was first verified via star tracking. Then, first SILEX optical communication was successfully performed in December 2001 with ARTEMIS at 31000 km. Following 12 months ARTEMIS orbit rising, SILEX commissioning phase was successfully achieved in spring 2003. Today, more than hundred successful optical communications have been achieved. On 1st of October 2003, the SILEX optical link was declared fully operational by the European and French space agencies. After a recall of SILEX architecture, design and on-ground verification, this paper reports on in-orbit results.

Planche, Gilles; Chorvalli, Vincent

2004-06-01

275

The orbit of GK Persei  

NASA Astrophysics Data System (ADS)

New spectroscopic observations of the old nova GK Per reveal the orbital period to be 1.996803 + or - 0.000007 days. The orbit is circular and the late-type component has a semiamplitude of 124 + or - 2 km/s. The hydrogen emission lines show a velocity variation in antiphase with the absorption lines with a semiamplitude of 34 + or - 5 km/s. The most probable masses are 0.25 solar mass for the K star and 0.9 solar mass for the white dwarf. The K star has obviously lost a lot of mass and is continuing to do so. An effort should be made to obtain photometry at the predicted times of occultation to see whether the system is eclipsing in order to further define the parameters of the system.

Crampton, D.; Fisher, W. A.; Cowley, A. P.

1986-01-01

276

The Orbiting Primate Experiment (OPE)  

NASA Technical Reports Server (NTRS)

Instrumentation and life support systems are described for an experiment to determine the physiological effects of long term space flight on unrestrained, minimally instrumented rhesus macaques flown in orbit for periods up to six months or one year. On return from orbit, vestibular, cardiovascular, and skeletal muscle function will be tested. Blood chemistry and hematological studies will be conducted as well as tests of the immunological competence of selected animals. Nasal, rectal, and throat swabs will be used for bacterial and viral studies, and histopathological and histochemical investigations will be be made of all organs using light and electron microscopy. The experiment is being considered as a payload for the biomedical experiment scientific satellite.

Bourne, G. H.; Debourne, M. N. G.; Mcclure, H. M.

1977-01-01

277

Of Orbits, Conics, and Grammar  

NASA Astrophysics Data System (ADS)

In the half-dozen or so years leading up to the publication of the Principia, Isaac Newton observed the comets of 1680 and 1682 and wrestled with the extent to which his law of gravitation could be applied. In time, he would see the connections between the four possible orbits of a satellite (circular, elliptical, parabolic, and hyperbolic) and the four curves produced by the careful carving of a cone. But if we look a little further into the conic sections, we find some interesting connections among the natural orbit of a satellite, ancient mathematics, and the roots of familiar words. Illuminating these connections for introductory physics students may help them to better understand the role of language and mathematics in the descriptions of science.

Henderson, Hugh

2005-02-01

278

Orbital changes during hypersonic aerocruise  

NASA Technical Reports Server (NTRS)

A novel mathematical approach that allows the analysis of orbital changes occurring during an aerocruise maneuver to be conducted in two distinct stages is presented. In the first stage, the aerodynamic turn is determined using a nondimensional form of the equations of motion that is free of singularities, and the way in which speed, altitude, angle of attack, and thrust direction should be chosen to maximize the aerodynamic turn for a given propellant expenditure is demonstrated. In the second analysis stage, the aerodynamic turn is translated into changes in the orbital elements with respect to the equatorial plane; analytic solutions for the initial arguments of latitude that maximize the change in inclination and in the longitude of the ascending node are given. As the initial inclination decreases toward zero, the optimal location moves from the apex toward the node.

Mease, Kenneth D.; Vinh, Nguyen X.; Lee, Jaemyong

1987-01-01

279

Analytic theory of orbit contraction  

NASA Technical Reports Server (NTRS)

The motion of a satellite in orbit, subject to atmospheric force and the motion of a reentry vehicle are governed by gravitational and aerodynamic forces. This suggests the derivation of a uniform set of equations applicable to both cases. For the case of satellite motion, by a proper transformation and by the method of averaging, a technique appropriate for long duration flight, the classical nonlinear differential equation describing the contraction of the major axis is derived. A rigorous analytic solution is used to integrate this equation with a high degree of accuracy, using Poincare's method of small parameters and Lagrange's expansion to explicitly express the major axis as a function of the eccentricity. The solution is uniformly valid for moderate and small eccentricities. For highly eccentric orbits, the asymptotic equation is derived directly from the general equation. Numerical solutions were generated to display the accuracy of the analytic theory.

Vinh, N. X.; Longuski, J. M.; Busemann, A.; Culp, R. D.

1977-01-01

280

Environmental dynamics at orbital altitudes  

NASA Technical Reports Server (NTRS)

The influence of real satellite aerodynamics on the determination of upper atmospheric density was investigated. A method of analysis of satellite drag data is presented which includes the effect of satellite lift and the variation in aerodynamic properties around the orbit. The studies indicate that satellite lift may be responsible for the observed orbit precession rather than a super rotation of the upper atmosphere. The influence of simplifying assumptions concerning the aerodynamics of objects in falling sphere analysis were evaluated and an improved method of analysis was developed. Wind tunnel data was used to develop more accurate drag coefficient relationships for studying altitudes between 80 and 120 Km. The improved drag coefficient relationships revealed a considerable error in previous falling sphere drag interpretation. These data were reanalyzed using the more accurate relationships. Theoretical investigations of the drag coefficient in the very low speed ratio region were also conducted.

Karr, G. R.

1976-01-01

281

Elliptical orbit performance computer program  

NASA Technical Reports Server (NTRS)

A FORTRAN coded computer program which generates and plots elliptical orbit performance capability of space boosters for presentation purposes is described. Orbital performance capability of space boosters is typically presented as payload weight as a function of perigee and apogee altitudes. The parameters are derived from a parametric computer simulation of the booster flight which yields the payload weight as a function of velocity and altitude at insertion. The process of converting from velocity and altitude to apogee and perigee altitude and plotting the results as a function of payload weight is mechanized with the ELOPE program. The program theory, user instruction, input/output definitions, subroutine descriptions and detailed FORTRAN coding information are included.

Myler, T. R.

1981-01-01

282

On-orbit spacecraft reliability  

NASA Technical Reports Server (NTRS)

Operational and historic data for 350 spacecraft from 52 U.S. space programs were analyzed for on-orbit reliability. Failure rates estimates are made for on-orbit operation of spacecraft subsystems, components, and piece parts, as well as estimates of failure probability for the same elements during launch. Confidence intervals for both parameters are also given. The results indicate that: (1) the success of spacecraft operation is only slightly affected by most reported incidents of anomalous behavior; (2) the occurrence of the majority of anomalous incidents could have been prevented piror to launch; (3) no detrimental effect of spacecraft dormancy is evident; (4) cycled components in general are not demonstrably less reliable than uncycled components; and (5) application of product assurance elements is conductive to spacecraft success.

Bloomquist, C.; Demars, D.; Graham, W.; Henmi, P.

1978-01-01

283

Lunar Orbiter: Moon and Earth  

NASA Technical Reports Server (NTRS)

The worlds first view of the Earth taken by a spacecraft from the vicinity of the Moon. The photo was transmitted to Earth by the United States Lunar Orbiter I and recieved at the NASA tracking station at Robledo de Chavela near Madrid, Spain. This crescent of the Earth was photographed August 23 at 16:35 GMT when the spacecraft was on its 16th orbit and just about to pass behind the Moon. This is the view the astronauts will have when they come around the backside of the Moon and face the Earth. The Earth is shown on the left of the photo with the U.S. east coast in the upper left, southern Europe toward the dark or night side of the Earth, and Antartica at the bottom of the Earth crescent. The surface of the Moon is shown on the right side of the photograph.

1966-01-01

284

Outgassing products from orbiter TPS materials  

NASA Technical Reports Server (NTRS)

The Space Transportation System (STS) orbiters are known to be significant sources of outgassing in low earth orbit (LEO). Infrared and mass spectra of residues and outgassing from orbiter thermal protection tile and an external blanket are presented. Several sources of methyl and phenyl methyl silicones are identified. About fifty pounds of silicones are estimated to be outgassed during an STS mission.

Harvey, Gale A.; Lash, Tom J.; Rawls, J. Richard

1995-01-01

285

Conversion Between Osculating and Mean Orbital Elements  

NASA Technical Reports Server (NTRS)

Osculating/Mean Orbital Element Conversion (C version) (OSMEANC) is a C-language computer program that performs precise conversions between osculating and mean classical orbital elements. OSMEANC can be used for precise design of spacecraft missions and maneuvers and precise calculation of planetary orbits. The program accounts for the full complexity of gravitational fields, including aspherical and third-body effects.

Guinn, Joseph; Chung, Min-Kun; Vincent, Mark

2006-01-01

286

Some Observations on Molecular Orbital Theory  

ERIC Educational Resources Information Center

A few flawed predictions in the context of homonuclear diatomic molecules are presented in order to introduce students to molecular orbital (MO) theory. A common misrepresentation of the relationship between the energy of an atomic orbital and the energy of the MO associated with the atomic orbital is illustrated.

Journal of Chemical Education, 2005

2005-01-01

287

Goce Satellite Orbit Simulation and Study  

NASA Astrophysics Data System (ADS)

In the 2007 year the first Earth Explorer Core mission the Gravity Field and Steady - State Ocean Circulation Mission GOCE as a part of ESA s Living Planet Programme is planned The Earth s gravity field will be measured by the gradiometer put into the satellite board The selected orbit of this satellite is near circular at the mean altitude 250 km Our work contains the research of the simulated orbit of the GOCE satellite For the orbital computations the Cowell numerical integration of the eighth order was used The GOCE satellite orbit description includes the relative comparison of the various forces acting on the satellite For the satellite motion determination the geopotential was described by means of the EGM96 model Additionally the satellite accelerations due to the atmospheric drag the Moon gravity the Sun gravity the planet gravity the solid Earth tides the oceanic tides the direct solar radiation pressure the undirect reflected solar radiation pressure and the relativity were computed Besides the reference satellite orbit i e the orbit closed to the GOCE satellite planned orbit as much as possible the various variants of the satellite orbit were obtained The satellite motion in these orbital variants is affected or not affected by the chosen forces for example by the direct solar radiation pressure and the undirect reflected solar radiation pressure with respect to the satellite motion in the reference orbit To obtain the influence of the chosen forces on the GOCE satellite orbit the comparison between the reference orbit and the

Bobojc, A.; Drozyner, A.

288

N-observations and radar orbits  

Microsoft Academic Search

Initial asteriod orbits are determined by a least squares adjustment of an arbitrary number (N) of optical and radar observations. The usual separation, into an orbit determination by three observations and a subsequent differential orbit improvement, is combined into a single algorithm. A priori information is used for very small arcs. Ephemerides very suitable for linking are obtained by strictly

Leif Kahl Kristensen

2007-01-01

289

Robert Hooke's Seminal Contribution to Orbital Dynamics  

E-print Network

1 Robert Hooke's Seminal Contribution to Orbital Dynamics Michael Nauenberg* During the second half's laws describing the observed orbital motion of a planet around the Sun. Robert Hooke (1635 or misunderstood. Key words: Robert Hooke; Isaac Newton; astronomy; orbital motion. Introduction One of the most

Belanger, David P.

290

Geological exploration from orbital altitudes  

USGS Publications Warehouse

The National Aeronautics & Space Administration is planning geologic exploration from orbiting spacecraft. For that purpose it is evaluating new and refined exploration tools, often called remote sensors, including devices that are sensitive to force fields, such as gravity gradient systems, and devices that record the reflection or emission of electromagnetic energy. Both passive electromagnetic sensors (those that rely on natural sources of illumination, such as the Sun) and active electromagnetic sensors (which use an artificial source of illumination) are being considered.

Badgley, Peter C.; Fischer, William A.; Lyon, Ronald J.P.

1965-01-01

291

The Orbit of the Moon  

NSDL National Science Digital Library

Martin Hackworth of Idaho State University has created this lab activity to help students measure the eccentricity of the moon's orbit. Students will need a drafting compass, protractor, vernier caliper, and a personal computer with a spreadsheet application. The lesson plan features an objective, needed equipment, general discussion, and procedure . In addition, the lesson concludes with six questions to test a student's overall knowledge of this lesson. The resource is provided as a pdf.

Hackworth, Martin

292

Introduction to complex orbital momenta  

Microsoft Academic Search

Summary  In this paper the orbital momentumj, until now considered as an integer discrete parameter in the radial Schrödinger wave equations, is allowed to take complex\\u000a values. The purpose of such an enlargement is not purely academic but opens new possibilities in discussing the connection\\u000a between potentials and scattering amplitudes. In particular it is shown that under reasonable assumptions, fulfilled by

T. Regge

1959-01-01

293

Ancient schwannoma of the orbit  

PubMed Central

The ancient schwannoma is a rare variant of a neurilemoma with a course typical of a slow-growing benign neoplasm. Histologically, it can be confused with a malignant mesenchymal tumor because of increased cellularity, nuclear pleomorphism, and hyperchromatism. Despite the degree of nuclear atypia, mitotic figures are absent. We describe the clinical and histopathologic features of an ancient schwannoma of the orbit. A need for early removal of such tumors is recommended to prevent complications. PMID:25136229

Kulkarni, Anjali S.; Anjum, Shaziya; Kokandakar, Hemant R.; Bindu, Rajan S.; Awargaonkar, Amarnath

2014-01-01

294

Viking orbiter system primary mission  

NASA Technical Reports Server (NTRS)

An overview of Viking Orbiter (VO) system and subsystem performances during the primary mission (the time period from VO-1 launch on August 20, 1975, through November 15, 1976) is presented. Brief descriptions, key design requirements, pertinent historical information, unique applications or situations, and predicted versus actual performances are included for all VO-1 and VO-2 subsystems, both individually and as an integrated system.

Goudy, J. R.

1977-01-01

295

Comet Orbits: Prediction, Nongravitational Effects  

NASA Technical Reports Server (NTRS)

The problems of calculating cometary orbits are discussed, with particular attention to that of predicting the returns of periodic comets. It is shown that the only inherent difficulty arises from the action of nongravitational forces. Recent progress toward an understanding of these forces is described in detail, both from the point of view of fitting the observations and of interpreting the forces in terms of the Whipple icy-conglomerate model.

Marsden, B. G.

1972-01-01

296

Remote orbital servicing system concept  

NASA Technical Reports Server (NTRS)

Increased applications of automation technology identified as necessary for NASA to carry out its missions within the constraints of future funding and available physical resources are described. A concept for a Remote Orbital Servicing System (ROSS) based on present teleoperator and robotics technology is presented. A single servicer design compatible with three specified spacecraft, capable of performing service to the same extent as manned extravehicular activity, controlled from a ground control station, and using currently available technology is conceptualized.

Meintel, A. J.; Schappell, R. T.

1982-01-01

297

On charge and orbital ordering  

NASA Astrophysics Data System (ADS)

In recent times there has been a resurgence of interest in the properties of transition metal oxides because of the wide range of physical properties that they exhibit. Recent developments in experimental techniques offer a direct probe to the novel types of ordering realised in these systems. Using first principle band structure calculations, we have critically examined^1 the results of resonant x-ray scattering experiments which are believed to directly probe charge and orbital ordering. Considering the specific case of La_0.5Sr_1.5MnO_4, we show that this technique actually probes most directly and sensitively small structural distortions in the system. Such distortions, often difficult to detect with more conventional techniques, invariably accompany and usually cause the orbital and charge orderings. In this sense, this technique is only an indirect probe of such types of ordering. Our results also provide a microscopic explanation of the novel types of charge and orbital ordering realized in this system and other doped manganites. 1. Priya Mahadevan, K. Terakura and D.D. Sarma, Phys. Rev. Lett. 87, 066404 (2001).

Mahadevan, Priya; Terakura, K.; Sarma, Dd

2002-03-01

298

Mars Reconnaissance Orbiter over Pole  

NASA Technical Reports Server (NTRS)

December 10, 2003

NASA's Mars Reconnaissance Orbiter passes over the planet's south polar region in this artist's concept illustration.

NASA plans to launch this multipurpose spacecraft in August 2005 to advance our understanding of Mars through detailed observation, to examine potential landing sites for future surface missions and to provide a high-data-rate communications relay for those missions.

The orbiter's shallow radar experiment, one of six science instruments on board, is designed to probe the internal structure of Mars' polar ice caps, as well as to gather information planet-wide about underground layers of ice, rock and, perhaps, liquid water that might be accessible from the surface.

Phobos, one of Mars' two moons, appears in the upper left corner of the illustration

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter Project for the NASA Office of Space Science, Washington. JPL's main industrial partner in the project, Lockheed Martin Space Systems, Denver, Colo., is building the spacecraft. The Italian Space Agency is providing the radar instrument.

2003-01-01

299

Excited states theory for optimized orbitals and valence optimized orbitals coupled-cluster doubles models  

E-print Network

Excited states theory for optimized orbitals and valence optimized orbitals coupled-cluster doubles May 2000; accepted 31 July 2000 We introduce an excited state theory for the optimized orbital coupled cluster doubles OO-CCD and valence optimized orbital coupled cluster doubles VOO-CCD models. The equations

Krylov, Anna I.

300

orbit their host star at distances closer than Mercury's orbit around the Sun (Fig. 1) --is  

E-print Network

orbit their host star at distances closer than Mercury's orbit around the Sun (Fig. 1 since the discovery7 in 2006 of three Neptune-mass planets on compact orbits around star HD69830 by the gravitational tug of an orbiting planet. The most dense multi- planet configurations have been observed

Schnaufer, Achim

301

APPLICATION OF OPTICAL TRACKING AND ORBIT ESTIMATION TO SATELLITE ORBIT TOMOGRAPHY  

E-print Network

AAS 13-824 APPLICATION OF OPTICAL TRACKING AND ORBIT ESTIMATION TO SATELLITE ORBIT TOMOGRAPHY Michael A. Shoemaker , Brendt Wohlberg , Richard Linares , and Josef Koller§ . Satellite orbit tomography, and selects nearly 200 resident space objects in low-Earth orbit as potential tracking targets. Over a chosen

Wohlberg, Brendt

302

The orbital record in stratigraphy  

NASA Technical Reports Server (NTRS)

Orbital signals are being discovered in pre-Pleistocene sediments. Due to their hierarchical nature these cycle patterns are complex, and the imprecision of geochronology generally makes the assignment of stratigraphic cycles to specific orbital cycles uncertain, but in sequences such as the limnic Newark Group under study by Olsen and pelagic Cretaceous sequence worked on by our Italo-American group the relative frequencies yield a definitive match to the Milankovitch hierarchy. Due to the multiple ways in which climate impinges on depositional systems, the orbital signals are recorded in a multiplicity of parameters, and affect different sedimentary facies in different ways. In platform carbonates, for example, the chief effect is via sea-level variations (possibly tied to fluctuating ice volume), resulting in cycles of emergence and submergence. In limnic systems it finds its most dramatic expression in alternations of lake and playa conditions. Biogenic pelagic oozes such as chalks and the limestones derived from them display variations in the carbonate supplied by planktonic organisms such as coccolithophores and foraminifera, and also record variations in the aeration of bottom waters. Whereas early studies of stratigraphic cyclicity relied mainly on bedding variations visible in the field, present studies are supplementing these with instrumental scans of geochemical, paleontological, and geophysical parameters which yield quantitative curves amenable to time-series analysis; such analysis is, however, limited by problems of distorted time-scales. My own work has been largely concentrated on pelagic systems. In these, the sensitivity of pelagic organisms to climatic-oceanic changes, combined with the sensitivity of botton life to changes in oxygen availability (commonly much more restricted in the Past than now) has left cyclic patterns related to orbital forcing. These systems are further attractive because (1) they tend to offer depositional continuity, and (2) presence of abundant microfossils yields close ties to geochronology. A tantalizing possibility that stratigraphy may yield a record of orbital signals unrelated to climate has turned up in magnetic studies of our Cretaceous core. Magnetic secular variations here carry a strong 39 ka periodicity, corresponding to the theoretical obliquity period of that time - Does the obliquity cycle perhaps have some direct influence on the magnetic field?

Fischer, Alfred G.

1992-01-01

303

ExoMars/TGO Science Orbit Design  

NASA Technical Reports Server (NTRS)

This paper describes the development of the science orbit for the 2016 ESA/NASA collaborative ExoMars/Trace Gas Orbiter (TGO) mission. The initial requirements for the ExoMars/TGO mission simply described the science orbit as circular with a 400 km altitude and a 74 deg inclination. Over the past year, the JPL mission design team worked with the TGO science teams to refine the science orbit requirements and recommend an orbit that would be operationally feasible, easy to maintain, and most important allow the science teams to best meet their objectives.

Long, Stacia; Lyons, Dan; Guinn, Joe; Lock, Rob

2012-01-01

304

Solar cell degradation in proton radiation orbits  

NASA Technical Reports Server (NTRS)

Significant discrepancies have been observed between predicted and actual in-orbit silicon solar array degradation in orbits other than LEO (low Earth orbits) and GEO (geosynchronous orbit). These discrepancies have been diagnosed to arise probably from a combination of a lack of appropriate solar cell test data and from inadequacies in the models that relate the unidirectional and mono-energetic proton test data to the omnidirectional flux-energy spectra actually found in orbit. Relative damage coefficients and solar cell power outputs were discussed, and also were presented in graph form. Silicon and gallium arsenide solar cells were considered.

Rauschenbach, H. S.; Yaung, J. Y.

1984-01-01

305

Payload/orbiter contamination control requirement study  

NASA Technical Reports Server (NTRS)

A study was conducted to determine and quantify the expected particulate and molecular on-orbit contaminant environment for selected space shuttle payloads as a result of major shuttle orbiter contamination sources. Individual payload susceptibilities to contamination are reviewed. The risk of payload degradation is identified and preliminary recommendations are provided concerning the limiting factors which may depend on operational activities associated with the payload/orbiter interface or upon independent payload functional activities. A basic computer model of the space shuttle orbiter which includes a representative payload configuration is developed. The major orbiter contamination sources, locations, and flux characteristics based upon available data have been defined and modeled.

Bareiss, L. E.; Rantanen, R. O.; Ress, E. B.

1974-01-01

306

Stationary occultations from low Earth orbit  

NASA Technical Reports Server (NTRS)

The process of stationary lunar occultations is considered for observers in LEO. The orbit of the Hubble Space Telescope (HST) is used as a prototype. The noncoplanarity of the HST and lunar orbits disrupts many of the expected stationary events, and orbital drag complicates the prediction problem. In a typical year, the apparent speed of the lunar limb seen by the HST is slower than a typical ground-based event only about 0.7 percent of the time. The orbit prediction can be wrong by as much as 20 deg in 53 days, with most of the error lying in the plane of the orbit.

Percival, Jeffrey W.

1993-01-01

307

Frozen orbit analysis in the Martian system  

NASA Astrophysics Data System (ADS)

A frozen orbit is an orbit whose time rate of change of the argument of the periapsis, the eccentricity, the semi major axis, or the angle of inclination (i) is approximately equal to zero. Martian frozen orbits are known to exist for polar trajectories with altitudes from 300 km to 1000 km. The objective of this study was to determine if other regions with characteristics similar to the known frozen orbits exist, taking into account the perturbative effects due to a 6 x 6 gravity field and atmospheric drag. First, the geopotential equation was derived for both spherical coordinates and the classical orbital elements. Next, a model for the atmospheric drag was developed. Using these two models, a FORTRAN computer model named ASAP (Artificial Satellite Analysis Program) was analyzed for accuracy. This program proved to be highly reliable, and was used to carry out further analysis. Two of the three trajectories planned for the future Mars Geoscience/Climatology Orbiter (MGCO) are frozen orbits. In order to determine the characteristics of w, e, a, and i of a frozen orbit, one of the MGCO frozen orbits was examined in both a 6 x 0 and a 6 x 6 gravity field. The analysis showed that the above orbital elements are not periodic over one orbital period (when in the presence of a 6 x 6 gravity field), but they are bounded over one axial period.

Foister, James W., III

1987-12-01

308

Orbital inflammatory disease in relapsing polychondritis.  

PubMed

We present a 73-year-old Chinese male with bilateral relapsing, remitting orbital inflammatory disease associated with relapsing polychondritis. He first presented with right orbital inflammation that did not improve despite antibiotic treatment. Computer tomography (CT) of the orbits showed a soft tissue mass along the roof of the orbit, which was biopsied, revealing acute on chronic inflammation. There was complete resolution of his orbital inflammation within 2 weeks of initiating systemic steroid treatment. He subsequently developed recurrent bouts of left orbital inflammation. One year later, he was diagnosed with relapsing polychondritis and subsequently developed multiple myeloma seven years later. Comanagement with a rheumatologist will be helpful to achieve control of the disease with judicious use of immunosuppression. Long-term follow-up of the patient will be necessary to monitor for malignant transformation of the orbital lesion, as well as the development of other hematologic malignancies. PMID:24831308

Teo, Livia; Choo, Chai Teck

2014-08-01

309

Topocentric Orbit Determination: Algorithms for the Next Generation Surveys  

E-print Network

Topocentric Orbit Determination: Algorithms for the Next Generation Surveys Andrea Milani1 October 2007 Manuscript pages: 53 Figures: 8; Tables: 10 1 #12;Running head: Orbit Determination steps: preliminary orbit determination, least squares orbit fitting, and quality control assessing

Knezevic, Zoran

310

CATALOG OF ORBIT DETERMINATION RESULTS FOR LINKED, AUTONOMOUS,  

E-print Network

CATALOG OF ORBIT DETERMINATION RESULTS FOR LINKED, AUTONOMOUS, INTERPLANETARY SATELLITE ORBIT for Astrodynamics Research University of Colorado Boulder, CO 80309 Revised 3 Feb 2006 #12;CATALOG OF ORBIT DETERMINATION RESULTS FOR LINKED, AUTONOMOUS, INTERPLANETARY SATELLITE ORBIT NAVIGATION (Li

Born, George

311

Orbital tumors: operative and therapeutic strategies.  

PubMed

The term "orbital tumors" includes diverse benign or malignant space-occupying lesions of the orbit, often leading to dystopia of the eyeball, motility disturbances, diplopia, visual field defects, and sometimes a complete loss of vision. Removing these tumors in a limited surgical field is challenging. Therefore, the preservation of function is a primary concern. We retrospectively reviewed 671 patients with orbital tumors from October 1999 to June 2014. Diagnosis on referral, presenting symptoms, radiological records, histology of the primary tumor or orbital metastasis, and treatment choice were analyzed. Among the 671 orbital tumors, 40% were accessed anteriorly, 36% via an orbitotomy with temporary osteotomy, and 23.9% underwent an orbital exenteration. As an illustration of the operative strategies with subsequent reconstructions, a distinction was made among the main indication groups: (1) function-preserving therapy for retrobulbar tumors, (2) malignant tumors of the conjunctiva and the eyelids, (3) exenteration of the orbit and subsequent reconstruction, and (4) operative and therapeutic strategy for orbital metastases. Adequate preoperative use of modern imaging techniques and thorough planning of the operation are crucial. Accurate histopathological diagnosis is crucial for planning appropriate therapeutic and surgical interventions. New innovative treatment concepts and surgical techniques arise from the close cooperation of related disciplines such as ophthalmology and neurosurgery. Although an orbital exenteration in patients with eyelid and conjunctival carcinomas can now often be avoided, eye-preserving treatment for locally advanced carcinomas of the conjunctiva and eyelid must be attempted. For extensive orbital malignancies, orbital exenteration is curative. In this context, primary closure of the orbit can improve the patient's quality of life and avoid subsequent complications. Concerning orbital metastasis, early diagnosis can preserve function and fulfil the esthetic demands of the patients. In palliative tumor disease, operative procedures such as orbital decompression or tumor debulking can reduce patient complaints and contribute to improved quality of life. PMID:25397713

Pförtner, R; Mohr, C; Daamen, J; Metz, A

2014-10-01

312

Orbital socket contracture: a complication of inflammatory orbital disease in patients with Wegener’s granulomatosis  

PubMed Central

Aim: To describe the clinical characteristics of orbital socket contracture in patients with Wegener’s granulomatosis (WG). Methods: A retrospective cohort study The medical records of 256 patients with WG examined at the National Institutes of Health from 1967 to 2004 were reviewed to identify patients with orbital socket contracture. Details of the orbital disease including Hertel exophthalmometry readings, radiological findings, and results of eye examinations were recorded. Orbital socket contracture was defined as orbital inflammation with proptosis followed by the development of enophthalmos and radiographic evidence of residual fibrotic changes in the orbit. To examine for risk factors in the development of a contracted orbit, patients with orbital socket contracture were compared to patients without contracture with respect to multiple variables including history of orbital surgery, orbital disease severity, and major organ system involvement. The main outcome measures were the clinical characteristics of orbital socket contracture associated with inflammatory orbital disease in patients with WG. Results: Inflammatory orbital disease occurred in 34 of 256 (13%) patients and detailed clinical data on 18 patients were available and examined. Orbital socket contracture occurred during the clinical course in six patients; the features included restrictive ophthalmopathy (five), chronic orbital pain (three), and ischaemic optic nerve disease (two) resulting in blindness (no light perception) in one patient. The orbital socket contracture occurred within 3 months of treatment with immunosuppressive medications for inflammatory orbital disease in five patients and was not responsive to immunosuppressive medications. The median degree of enophthalmos in the contracted orbit compared with the fellow eye was 2.8 mm (range 1.5–3.5 mm) by Hertel exophthalmometry. There were no risk factors that predicted development of orbital socket contracture. Conclusions: In six patients with WG and active inflammatory orbital disease, orbital socket contracture occurred during the treatment course with systemic immunosuppressive medications. The orbital socket contracture, presumably caused by orbital fibrosis, led to enophthalmos, restrictive ophthalmopathy, chronic orbital pain, and optic nerve disease and was not responsive to immunosuppressive therapy. Orbital socket contracture has not been previously reported as a complication of inflammatory orbital disease associated with WG and was an important cause of visual morbidity in our cohort of patients. PMID:15774931

Talar-Williams, C; Sneller, M C; Langford, C A; Smith, J A; Cox, T A; Robinson, M R

2005-01-01

313

Lunar resource surveys from orbit  

NASA Technical Reports Server (NTRS)

The chemical composition of lunar soil and rocks is known now for nine surface sites, by analysis of returned samples. Three classes of silicate material, mare basalt, KREEP, and highland material (sometimes called ANT) have been identified as major components. Gamma-ray and X-ray instruments have mapped the Apollo 15 and 16 ground tracks for major elements, K, and Th. It is hoped that the Lunar Polar Orbiter will carry instruments capable of producing a chemical map of the entire moon. The most exciting possibility is that ice may exist in shadowed regions near the lunar pole.

Arnold, J. R.

1977-01-01

314

Environmental dynamics at orbital altitudes  

NASA Technical Reports Server (NTRS)

The work reported involved the improvement of aerodynamic theory for free molecular and transition flow regimes. The improved theory was applied to interpretation of the dynamic response of objects traveling through the atmosphere. Satellite drag analysis includes analysis methods, atmospheric super rotation effects, and satellite lift effects on orbital dynamics. Transition flow regimes were studied with falling sphere data and errors resulting in inferred atmospheric parameters from falling sphere techniques. Improved drag coefficients reveal considerable error in previous falling sphere data. The drag coefficient has been studied for the entire spectrum of Knudsen Number and speed ratio, with particular emphasis on the theory of the very low-speed ratio regime.

Karr, G. R.

1976-01-01

315

Pearls of Orbital Trauma Management  

PubMed Central

Orbital fractures account for a significant portion of traumatic facial injuries. Although plastic surgery literature is helpful, additional pearls and insights are provided in this article from the experience of an oculoplastic surgeon. The fundamentals remain the same, but the perceptions differ and provide a healthy perspective on a long-standing issue. The most important thing to remember is that the optimal management plan is often variable, and the proper choice regarding which plan to choose rests upon the clinical scenario and the surgeon having an honest perception of his or her level of expertise and comfort level. PMID:22550464

Roth, Forrest S.; Koshy, John C.; Goldberg, Jonathan S.; Soparkar, Charles N.S.

2010-01-01

316

Orbital debris: A technical assessment  

NASA Technical Reports Server (NTRS)

To acquire an unbiased technical assessment of (1) the research needed to better understand the debris environment, (2) the necessity and means of protecting spacecraft against the debris environment, and (3) potential methods of reducing the future debris hazard, NASA asked the National Research Council to form an international committee to examine the orbital debris issue. The committee was asked to draw upon available data and analyses to: characterize the current debris environment, project how this environment might change in the absence of new measures to alleviate debris proliferation, examine ongoing alleviation activities, explore measures to address the problem, and develop recommendations on technical methods to address the problems of debris proliferation.

Gleghorn, George; Asay, James; Atkinson, Dale; Flury, Walter; Johnson, Nicholas; Kessler, Donald; Knowles, Stephen; Rex, Dietrich; Toda, Susumu; Veniaminov, Stanislav

1995-01-01

317

The Orbiting Carbon Observatory (OCO)  

NASA Technical Reports Server (NTRS)

CO2 is the principal human generated driver of climate change. Accurate forecasting of future climate requires an improved understanding of the global carbon cycle and its interaction with the climate system. The Orbiting Carbon Observatory (OCO) will make global, space-based observations of atmospheric CO2 with the precision, resolution, and coverage needed to understand sources and sinks. OCO data will provide critical information for decision makers including the scientific basis for policy formulation, guide for carbon management strategies and treaty monitoring.

Miller, Charles E.

2005-01-01

318

Viking orbiter stereo imaging catalog  

NASA Technical Reports Server (NTRS)

The extremely long missions of the two Viking Orbiter spacecraft produced a wealth of photos of surface features. Many of which can be used to form stereo images allowing the earth-bound student of Mars to examine the subject in 3-D. This catalog is a technical guide to the use of stereo coverage within the complex Viking imaging data set. Since that data set is still growing (January, 1980, about 3 1/2 years after the mission began), a second edition of this catalog is planned with completion expected about November, 1980.

Blasius, K. R.; Vetrone, A. V.; Martin, M. D.

1980-01-01

319

Orbital Evolution of Scattered Planets  

E-print Network

A simple dynamical model is employed to study the possible orbital evolution of scattered planets and phase plane analysis is used to classify the parameter space and solutions. Our results reconfirm that there is always an increase in eccentricity when the planet was scattered to migrate outward when the initial eccentricity is zero. Applying our study on the Solar System and considering the existence of the Kuiper Belt, this conclusion implies that Neptune was dynamically coupled with the Kuiper Belt in the early phase of the Solar System, which is consistent with the simulational model in Thommes, Duncan & Levison (1999).

Li-Chin Yeh; Ing-Guey Jiang

2001-07-03

320

Comet C/2011 W3 (Lovejoy): Orbit Determination, Outbursts, Disintegration of Nucleus, Dust-tail Morphology, and Relationship to New Cluster of Bright Sungrazers  

NASA Astrophysics Data System (ADS)

We describe the physical and orbital properties of C/2011 W3. After surviving perihelion passage, the comet was observed to undergo major physical changes. The permanent loss of the nuclear condensation and the formation of a narrow spine tail were observed first at Malargue, Argentina, on December 20 and then systematically at Siding Spring, Australia. The process of disintegration culminated with a terminal fragmentation event on December 17.6 UT. The postperihelion dust tail, observed for ~3 months, was the product of activity over <2 days. The nucleus' breakup and crumbling were probably caused by thermal stress due to the penetration of the intense heat pulse deep into the nucleus' interior after perihelion. The same mechanism may be responsible for cascading fragmentation of sungrazers at large heliocentric distances. The delayed response to the hostile environment in the solar corona is at odds with the rubble-pile model, since the residual mass of the nucleus, estimated at ~1012 g (equivalent to a sphere 150-200 m across) just before the terminal event, still possessed nontrivial cohesive strength. The high production rates of atomic oxygen, observed shortly after perihelion, are compatible with a subkilometer-sized nucleus. The spine tail—the product of the terminal fragmentation—was a synchronic feature, whose brightest part contained submillimeter-sized dust grains, released at velocities of up to 30 m s-1. The loss of the nuclear condensation prevented an accurate orbital-period determination by traditional techniques. Since the missing nucleus must have been located on the synchrone, whose orientation and sunward tip have been measured, we compute the astrometric positions of this missing nucleus as the coordinates of the points of intersection of the spine tail's axis with the lines of forced orbital-period variation, derived from the orbital solutions based on high-quality preperihelion astrometry from the ground. The resulting orbit gives 698 ± 2 yr for the osculating orbital period, showing that C/2011 W3 is the first member of the expected new, 21st-century cluster of bright Kreutz-system sungrazers, whose existence was predicted by these authors in 2007. From the spine tail's evolution, we determine that its measured tip, populated by dust particles 1-2 mm in diameter, receded antisunward from the computed position of the missing nucleus. The bizarre appearance of the comet's dust tail in images taken only hours after perihelion with the coronagraphs on board the SOHO and STEREO spacecraft is readily understood. The disconnection of the comet's head from the tail released before perihelion and an apparent activity attenuation near perihelion have a common cause—sublimation of all dust at heliocentric distances smaller than about 1.8 solar radii. The tail's brightness is strongly affected by forward scattering of sunlight by dust. From an initially broad range of particle sizes, the grains that were imaged the longest had a radiation-pressure parameter ? ~= 0.6, diagnostic of submicron-sized silicate grains and consistent with the existence of the dust-free zone around the Sun. The role and place of C/2011 W3 in the hierarchy of the Kreutz system and its genealogy via a 14th-century parent suggest that it is indirectly related to the celebrated sungrazer X/1106 C1, which, just as the first-generation parent of C/2011 W3, split from a common predecessor during the previous return to perihelion.

Sekanina, Zdenek; Chodas, Paul W.

2012-10-01

321

COMET C/2011 W3 (LOVEJOY): ORBIT DETERMINATION, OUTBURSTS, DISINTEGRATION OF NUCLEUS, DUST-TAIL MORPHOLOGY, AND RELATIONSHIP TO NEW CLUSTER OF BRIGHT SUNGRAZERS  

SciTech Connect

We describe the physical and orbital properties of C/2011 W3. After surviving perihelion passage, the comet was observed to undergo major physical changes. The permanent loss of the nuclear condensation and the formation of a narrow spine tail were observed first at Malargue, Argentina, on December 20 and then systematically at Siding Spring, Australia. The process of disintegration culminated with a terminal fragmentation event on December 17.6 UT. The postperihelion dust tail, observed for {approx}3 months, was the product of activity over <2 days. The nucleus' breakup and crumbling were probably caused by thermal stress due to the penetration of the intense heat pulse deep into the nucleus' interior after perihelion. The same mechanism may be responsible for cascading fragmentation of sungrazers at large heliocentric distances. The delayed response to the hostile environment in the solar corona is at odds with the rubble-pile model, since the residual mass of the nucleus, estimated at {approx}10{sup 12} g (equivalent to a sphere 150-200 m across) just before the terminal event, still possessed nontrivial cohesive strength. The high production rates of atomic oxygen, observed shortly after perihelion, are compatible with a subkilometer-sized nucleus. The spine tail-the product of the terminal fragmentation-was a synchronic feature, whose brightest part contained submillimeter-sized dust grains, released at velocities of up to 30 m s{sup -1}. The loss of the nuclear condensation prevented an accurate orbital-period determination by traditional techniques. Since the missing nucleus must have been located on the synchrone, whose orientation and sunward tip have been measured, we compute the astrometric positions of this missing nucleus as the coordinates of the points of intersection of the spine tail's axis with the lines of forced orbital-period variation, derived from the orbital solutions based on high-quality preperihelion astrometry from the ground. The resulting orbit gives 698 {+-} 2 yr for the osculating orbital period, showing that C/2011 W3 is the first member of the expected new, 21st-century cluster of bright Kreutz-system sungrazers, whose existence was predicted by these authors in 2007. From the spine tail's evolution, we determine that its measured tip, populated by dust particles 1-2 mm in diameter, receded antisunward from the computed position of the missing nucleus. The bizarre appearance of the comet's dust tail in images taken only hours after perihelion with the coronagraphs on board the SOHO and STEREO spacecraft is readily understood. The disconnection of the comet's head from the tail released before perihelion and an apparent activity attenuation near perihelion have a common cause-sublimation of all dust at heliocentric distances smaller than about 1.8 solar radii. The tail's brightness is strongly affected by forward scattering of sunlight by dust. From an initially broad range of particle sizes, the grains that were imaged the longest had a radiation-pressure parameter {beta} {approx_equal} 0.6, diagnostic of submicron-sized silicate grains and consistent with the existence of the dust-free zone around the Sun. The role and place of C/2011 W3 in the hierarchy of the Kreutz system and its genealogy via a 14th-century parent suggest that it is indirectly related to the celebrated sungrazer X/1106 C1, which, just as the first-generation parent of C/2011 W3, split from a common predecessor during the previous return to perihelion.

Sekanina, Zdenek; Chodas, Paul W., E-mail: Zdenek.Sekanina@jpl.nasa.gov, E-mail: Paul.W.Chodas@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

2012-10-01

322

Orbital floor reconstruction with ethyl-2-cyanoacrylate.  

PubMed

The orbital floor is one of the most frequently broken bones in maxillofacial fracture, and orbital reconstruction is needed in many cases. Various materials are used for orbital floor reconstruction. We report here orbital reconstruction using autologous orbital bone with cyanoacrylate. Entrapped soft tissues were freed and repositioned intraorbitally and bone fragments were gathered with a microscope simultaneously. The bone fragments were fixed to a board of bone with ethyl-2-cyanoacrylate and returned to the orbital fracture site. Of 96 fresh orbital floor fractures, this method was used for 31 (32.3%) patients. Simple reduction was performed in 48 patients. Bone graft with iliac crest was performed in the other 12 patients. Reconstruction with alloplastic materials was performed in 5 patients. Diplopia was corrected in 26 patients on whom this method was performed. The reconstructed bone collapsed into the maxillary sinus in 1 patient who underwent iliac bone graft on reoperation. Another 4 patients did not show diplopia preoperatively. None of the patients showed enophthalmos, foreign body reaction, or infection postoperatively. We were able to perform orbital bone reconstruction with autologous orbital bone without another donor site in 30 (62.5%) of 48 cases that required grafting. The indications for this method are that a sufficient quantity of bone fragments can be obtained and returned on a board of bone which can be stabilized in the orbit without collapsing into the maxillary sinus. Good results were obtained, and we consider this to be a safe and useful method. PMID:24149407

Nemoto, Hitoshi; Ito, Yoshinori; Kasai, Yoshiaki; Maruyama, Naoki; Kimura, Naohiro; Sumiya, Noriyoshi

2015-02-01

323

Mission Design for the Lunar Reconnaissance Orbiter  

NASA Technical Reports Server (NTRS)

The Lunar Reconnaissance Orbiter (LRO) will be the first mission under NASA's Vision for Space Exploration. LRO will fly in a low 50 km mean altitude lunar polar orbit. LRO will utilize a direct minimum energy lunar transfer and have a launch window of three days every two weeks. The launch window is defined by lunar orbit beta angle at times of extreme lighting conditions. This paper will define the LRO launch window and the science and engineering constraints that drive it. After lunar orbit insertion, LRO will be placed into a commissioning orbit for up to 60 days. This commissioning orbit will be a low altitude quasi-frozen orbit that minimizes stationkeeping costs during commissioning phase. LRO will use a repeating stationkeeping cycle with a pair of maneuvers every lunar sidereal period. The stationkeeping algorithm will bound LRO altitude, maintain ground station contact during maneuvers, and equally distribute periselene between northern and southern hemispheres. Orbit determination for LRO will be at the 50 m level with updated lunar gravity models. This paper will address the quasi-frozen orbit design, stationkeeping algorithms and low lunar orbit determination.

Beckman, Mark

2007-01-01

324

Constrained orbital intercept-evasion  

NASA Astrophysics Data System (ADS)

An effective characterization of intercept-evasion confrontations in various space environments and a derivation of corresponding solutions considering a variety of real-world constraints are daunting theoretical and practical challenges. Current and future space-based platforms have to simultaneously operate as components of satellite formations and/or systems and at the same time, have a capability to evade potential collisions with other maneuver constrained space objects. In this article, we formulate and numerically approximate solutions of a Low Earth Orbit (LEO) intercept-maneuver problem in terms of game-theoretic capture-evasion guaranteed strategies. The space intercept-evasion approach is based on Liapunov methodology that has been successfully implemented in a number of air and ground based multi-player multi-goal game/control applications. The corresponding numerical algorithms are derived using computationally efficient and orbital propagator independent methods that are previously developed for Space Situational Awareness (SSA). This game theoretical but at the same time robust and practical approach is demonstrated on a realistic LEO scenario using existing Two Line Element (TLE) sets and Simplified General Perturbation-4 (SGP-4) propagator.

Zatezalo, Aleksandar; Stipanovic, Dusan M.; Mehra, Raman K.; Pham, Khanh

2014-06-01

325

Mars Rotational and Orbital Dynamics  

NASA Technical Reports Server (NTRS)

The Rotation and Orbit Dynamics experiment is based on measuring the Doppler range to Pathfinder using the radio link. Mars rotation about it's pole causes a signature in the data with a daily minimum when the lander is closest to the Earth. Changes in the daily signature reveal information about the planetary interior, through its effect on Mars' precession and nutation. The signature also is sensitive to variations in Mars' rotation rate as the mass of the atmosphere increases and decreases as the polar caps are formed in winter and evaporate in spring. Long term signatures in the range to the lander are caused by asteroids perturbing Mars' orbit. Analysis of these perturbations allows the determination of the masses of asteroids.

Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

1997-01-01

326

Orbital Debris Observations with WFCAM  

NASA Astrophysics Data System (ADS)

The United Kingdom Infrared Telescope has been operating for 35 years on the summit of Mauna Kea as a premier Infrared astronomical facility. In its 35th year the telescope has been turned over to a new operating group consisting of University of Arizona, University of Hawaii and the LM Advanced Technology Center. UKIRT will continue its astronomical mission with a portion of observing time dedicated to orbital debris and Near Earth Object detection and characterization. During the past 10 years the UKIRT Wide Field CAMera (WFCAM) has been performing large area astronomical surveys in the J, H and K bands. The data for these surveys have been reduced by the Cambridge Astronomical Survey Unit in Cambridge, England and archived by the Wide Field Astronomy Unit in Edinburgh, Scotland. During January and February of 2014 the Wide Field CAMera (WFCAM) was used to scan through the geostationary satellite belt detecting operational satellites as well as nearby debris. Accurate photometric and astrometric parameters have been developed by CASU for each of the detections and all data has been archived by WFAU. This paper will present the January and February results of the orbital debris surveys with WFCAM.

Kendrick, R.; Mann, B.; Read, M.; Kerr, T.; Irwin, M.; Cross, N.; Bold, M.,; Varricatt, W.; Madsen, G.

2014-09-01

327

Achromatic orbital angular momentum generator  

NASA Astrophysics Data System (ADS)

We describe a novel approach for generating light beams that carry orbital angular momentum (OAM) by means of total internal reflection in an isotropic medium. A continuous space-varying cylindrically symmetric reflector, in the form of two glued hollow axicons, is used to introduce a nonuniform rotation of polarization into a linearly polarized input beam. This device acts as a full spin-to-orbital angular momentum convertor. It functions by switching the helicity of the incoming beam?s polarization, and by conservation of total angular momentum thereby generates a well-defined value of OAM. Our device is broadband, since the phase shift due to total internal reflection is nearly independent of wavelength. We verify the broad-band behaviour by measuring the conversion efficiency of the device for three different wavelengths corresponding to the RGB colours, red, green and blue. An average conversion efficiency of 95% for these three different wavelengths is observed. This device may find applications in imaging from micro- to astronomical systems where a white vortex beam is needed.

Bouchard, Frédéric; Mand, Harjaspreet; Mirhosseini, Mohammad; Karimi, Ebrahim; Boyd, Robert W.

2014-12-01

328

Military manoeuvres in synchronous orbit  

NASA Astrophysics Data System (ADS)

The Defense Support Satellite program (DSP) is described, together with a series of maneuvers performed by DSP spacecraft in 1982. The satellites are equipped with IR sensors for early warning of a missile attack. The program has been expanded in recent year to account for possible attacks using submarine launchers. The satellite designated 1982-19A was launched in Mar. 1982 into a 35,521 by 35,600 km orbit. A satellite 1982-19A was sent to replace, 1981-25A, moved toward a 35,778 km GEO orbit the next day. 1982-19A then took over western Atlantic surveillance from a position over Brasil. 1981-25A was then maneuvered to replace 1979-53A over the eastern Pacific. 1979-53A was moved to a position over Ecuador at 86 deg W. Possible applications of 1979-53A, including as a test vehicle for on-board laser countermeasures, or as a tracking target for calibration of GEODSS optical systems, are discussed.

Kenden, A.

1983-02-01

329

Dexterous Orbital Servicing System (DOSS)  

NASA Technical Reports Server (NTRS)

The Dexterous Orbiter Servicing System (DOSS) is a dexterous robotic spaceflight system that is based on the manipulator designed as part of the Flight Telerobotics Servicer program for the Space Station Freedom and built during a 'technology capture' effort that was commissioned when the FTS was cancelled from the Space Station Freedom program. The FTS technology capture effort yielded one flight manipulator and the 1 g hydraulic simulator that had been designed as an integrated test tool and crew trainer. The DOSS concept was developed to satisfy needs of the telerobotics research community, the space shuttle, and the space station. As a flight testbed, DOSS would serve as a baseline reference for testing the performance of advanced telerobotics and intelligent robotics components. For shuttle, the DOSS, configured as a movable dexterous tool, would be used to provide operational flexibility for payload operations and contingency operations. As a risk mitigation flight demonstration, the DOSS would serve the International Space Station to characterize the end to end system performance of the Special Purpose Dexterous Manipulator performing assembly and maintenance tasks with actual ISSA orbital replacement units. Currently, the most likely entrance of the DOSS into spaceflight is a risk mitigation flight experiment for the International Space Station.

Price, Charles R.; Berka, Reginald B.; Chladek, John T.

1994-01-01

330

Introducing the Moon's Orbital Eccentricity  

NASA Astrophysics Data System (ADS)

I present a novel way to introduce the lunar orbital eccentricity in introductory astronomy courses. The Moon is perhaps the clearest illustration of the general orbital elements such as inclination, ascending node, eccentricity, perigee, and so on. Furthermore, I like the students to discover astronomical phenomena for themselves, by means of a guided exercise, rather than just telling them the facts.1 The inclination and nodes may be found by direct observation, monitoring carefully the position of the Moon among the stars. Even the regression of the nodes may be discovered in this way2 To find the eccentricity from students' observations is also possible,3 but that requires considerable time and effort. if a whole class should discover it in a short time, here is a method more suitable for a one-day class or home assignment. The level I aim at is, more or less, advanced high school or first-year college students. I assume them to be acquainted with celestial coordinates and the lunar phases, and to be able to use algebra and trigonometry.

Oostra, Benjamin

2014-11-01

331

On-orbit Passive Thermography  

NASA Technical Reports Server (NTRS)

On July 12, 2006, British-born astronaut Piers Sellers became the first person to conduct thermal nondestructive evaluation experiments in space, demonstrating the feasibility of a new tool for detecting damage to the reinforced carbon-carbon (RCC) structures of the Shuttle. This new tool was an EVA (Extravehicular Activity, or spacewalk) compatible infrared camera developed by NASA engineers. Data was collected both on the wing leading edge of the Orbiter and on pre-damaged samples mounted in the Shuttle s cargo bay. A total of 10 infrared movies were collected during the EVA totaling over 250 megabytes of data. Images were downloaded from the orbiting Shuttle to Johnson Space Center for analysis and processing. Results are shown to be comparable to ground-based thermal inspections performed in the laboratory with the same type of camera and simulated solar heating. The EVA camera system detected flat-bottom holes as small as 2.54cm in diameter with 50% material loss from the back (hidden) surface in RCC during this first test of the EVA IR Camera. Data for the time history of the specimen temperature and the capability of the inspection system for imaging impact damage are presented.

Howell, Patricia A.; Winfree, William P.; Cramer, K. Elliott

2008-01-01

332

Safety in earth orbit study. Volume 4: Space shuttle orbiter: Safety requirements and guidelines on-orbit phase  

NASA Technical Reports Server (NTRS)

Safety requirements and guidelines are listed for the space shuttle orbiter and for its interface with other vehicles. The requirements and guidelines are specific to the hazards and emergencies in earth orbit. The requirements and guidelines for the orbiter are those with respect to vehicle design, safety devices, warning devices, operational procedures, and residual hazards. The requirements and guidelines for interface with the space station, upper stage vehicles, and sortie payloads are imposed on these vehicles to ensure the safety of the shuttle orbiter. The rationale for the safety requirements and guidelines is also discussed.

1972-01-01

333

The performance of Space-Based Radars (SBR) orbiting on elliptical orbits  

NASA Astrophysics Data System (ADS)

The performance of Space-Based Radars (SBR) orbiting on elliptical orbits is discussed. Their ability to detect air-breathing targets is analyzed as a function of the antenna look angle, the orbital parameters of the satellite, the number of radio pulses transmitted and the peak power of the radar. The results show that the minimum detectable velocities of the SBR tend to degrade as the satellite approaches the apogee of its orbit. Depending on the orbital parameters of the satellite, the advantage of more extended coverage when the satellite is at the apogee of its orbit could be hindered by the poorer performance of the radar.

Faubert, D.; Kerr, M. P.

1988-12-01

334

Determination and prediction of Magellan's orbit  

NASA Technical Reports Server (NTRS)

The Magellan spacecraft has been systematically mapping the surface of Venus since September 15, 1990, using a synthetic aperture radar. The spacecraft orbit about Venus is nearly polar, with an orbital period of 3.26 hours and periapsis altitude of 295 km. The radiometric measurements and the data reduction method used to determine and predict the spacecraft state are described. Orbit determination and prediction results are given for the first 146 days of mapping (through February 8, 1991, 60 percent of the first rotation of Venus). Orbit accuracy requirements of 150 meters in the radial position, and 1 km in the along-track and cross-track positions are shown to be met, but with exceptions. All error requirements were exceeded during a combined period of limited in-plane orbit observability due to earth-orbit relative geometry, and increased measurement noise due to superior conjunction.

Engelhardt, D. B.; Mcnamee, J. B.; Wong, S. K.; Bonneau, F. G.; Graat, E. J.; Haw, R. J.; Kronschnabl, G. R.; Ryne, M. S.

1991-01-01

335

Orbit determination for ISRO satellite missions  

NASA Astrophysics Data System (ADS)

Indian Space Research Organisation (ISRO) has been successful in using the in-house developed orbit determination and prediction software for satellite missions of Bhaskara, Rohini and APPLE. Considering the requirements of satellite missions, software packages are developed, tested and their accuracies are assessed. Orbit determination packages developed are SOIP, for low earth orbits of Bhaskara and Rohini missions, ORIGIN and ODPM, for orbits related to all phases of geo-stationary missions and SEGNIP, for drift and geo-stationary orbits. Software is tested and qualified using tracking data of SIGNE-3, D5-B, OTS, SYMPHONIE satellites with the help of software available with CNES, ESA and DFVLR. The results match well with those available from these agencies. These packages have supported orbit determination successfully throughout the mission life for all ISRO satellite missions. Member-Secretary

Rao, Ch. Sreehari; Sinha, S. K.

336

RHIC BPM system average orbit calculations  

SciTech Connect

RHIC beam position monitor (BPM) system average orbit was originally calculated by averaging positions of 10000 consecutive turns for a single selected bunch. Known perturbations in RHIC particle trajectories, with multiple frequencies around 10 Hz, contribute to observed average orbit fluctuations. In 2006, the number of turns for average orbit calculations was made programmable; this was used to explore averaging over single periods near 10 Hz. Although this has provided an average orbit signal quality improvement, an average over many periods would further improve the accuracy of the measured closed orbit. A new continuous average orbit calculation was developed just prior to the 2009 RHIC run and was made operational in March 2009. This paper discusses the new algorithm and performance with beam.

Michnoff,R.; Cerniglia, P.; Degen, C.; Hulsart, R.; et al.

2009-05-04

337

Orbit Design of Earth-Observation Satellite  

NASA Astrophysics Data System (ADS)

The purpose of this study is to design a reliable orbit for a medium-resolution scientific satellite to observe Earth for developmental issues such as water resources, agricultural, and industrial. To meet this objective this study firstly, defines the mission, secondly, determines mission constraints, thirdly, design the attitude and orbit control system. As for the observation requirements, and the revisit time are provided as a function of the orbital parameters. Initial orbital parameters are obtained by optimal analysis between observation characteristics and attitude and orbit maintenance costs. Long term station-keeping strategies will be provided for the proposed solutions. Impulsive control will be investigated to provide a reliable and affordable attitude and orbit control system.

Owis, Ashraf

338

Orbital Granulomatosis With Polyangiitis (Wegener Granulomatosis)  

PubMed Central

The pathology of granulomatosis with polyangiitis (GPA), formerly Wegener granulomatosis, typically features a granulomatous and sometimes necrotizing vasculitis targeting the respiratory tract and kidneys. However, orbital involvement occurs in up to 60% of patients and is frequently the first or only clinical presentation in patients with systemic or limited forms of GPA. Orbital GPA can cause significant morbidity and potentially lead to complete loss of vision and permanent facial deformity. Fortunately, GPA is highly responsive to medical treatment with corticosteroids combined with cyclophosphamide or, more recently, rituximab. Therefore, it is imperative for this disease to be accurately diagnosed on orbital biopsy and distinguished from other histologically similar orbital lesions. Herein, we review the clinical and pathologic findings of orbital GPA, focusing on the differentiation of this disease from other inflammatory orbital lesions. PMID:25076302

Muller, Karra; Lin, Jonathan H.

2014-01-01

339

Electric Propulsion for Low Earth Orbit Constellations  

NASA Technical Reports Server (NTRS)

Hall effect electric propulsion was evaluated for orbit insertion, satellite repositioning, orbit maintenance and de-orbit applications for a sample low earth orbit satellite constellation. Since the low masses of these satellites enable multiple spacecraft per launch, the ability to add spacecraft to a given launch was used as a figure of merit. When compared to chemical propulsion, the Hall thruster system can add additional spacecraft per launch using planned payload power levels. One satellite can be added to the assumed four satellite baseline chemical launch without additional mission times. Two or three satellites may be added by providing part of the orbit insertion with the Hall system. In these cases orbit insertion times were found to be 35 and 62 days. Depending, on the electric propulsion scenario, the resulting launch vehicle savings is nearly two, three or four Delta 7920 launch vehicles out of the chemical baseline scenario's eight Delta 7920 launch vehicles.

Oleson, Steven R.; Sankovic, John M.

1998-01-01

340

Electric Propulsion for Low Earth Orbit Constellations  

NASA Technical Reports Server (NTRS)

Hall Effect electric propulsion was evaluated for orbit insertion, satellite repositioning, orbit maintenance and de-orbit applications for a sample low earth orbit satellite constellation. Since the low masses of these satellites enable multiple spacecraft per launch, the ability to add spacecraft to a given launch was used as a figure of merit. When compared to chemical propulsion, the Hall thruster system can add additional spacecraft per launch using planned payload power levels. One satellite can be added to the assumed four satellite baseline chemical launch without additional mission times. Two or three satellites may be added by providing part of the orbit insertion with the Hall system. In these cases orbit insertion times were found to be 35 and 62 days. Depending on the electric propulsion scenario, the resulting launch vehicle savings is nearly two, three or four Delta 7920 launch vehicles out of the chemical baseline scenarios eight Delta 7920 launch vehicles.

Oleson, Steven R.; Sankovic, John M.

1998-01-01

341

Heliocentric interplanetary low thrust trajectory optimization program, supplement 1  

NASA Technical Reports Server (NTRS)

The modifications and improvements made to the HILTOP electric propulsion trajectory optimization computer program up through the end of 1974 is described. New program features include the simulation of power degradation, housekeeping power, launch asymptote declination optimization, and powered and unpowered ballistic multiple swingby missions with an optional deep space burn. The report contains the new analysis describing these features, a complete description of program input quantities, and sample cases of computer output illustrating the new program capabilities.

Mann, F. I.; Horsewood, J. L.

1974-01-01

342

The three images on the front of this poster show our galactic neighbor, the Andromeda Galaxy. This galaxy, also  

E-print Network

be spotted with the naked eye as a fuzzy blob. Like our own galaxy, Andromeda is a large spiral galaxy. The top image may look familiar, because it was made with visible light--the light we see with our eyes. It is in a solar, Earth- trailing orbit as it observes the infrared universe. Ultraviolet: Blue in the stars image

343

NORAD TLE Conversion from Osculating Orbital Element  

NASA Astrophysics Data System (ADS)

The NORAD type Two Line Element (TLE) was obtained from the osculating orbital elements by an iterative approximation procedure. The mathematical model was presented and computer program was developed for the conversion. The osculating orbital elements of the KOMPSAT-1 were converted into the NORAD TLE. Then the effect of the SGP4 atmospheric drag coefficient (B*) was analyzed by comparison of the orbit propagation results with different B* values.

Lee, Byoung-Sun

2002-12-01

344

LTU Physlet: Elliptical Orbits Around the Earth  

NSDL National Science Digital Library

This applet shows the motions of three bodies orbiting the earth with the same initial position but varying initial velocities. The result show two different elliptical orbits and a circular geosynchronous orbit. Standard controls allow the user to start, pause, step, and reset the animation. This is part of a large collection of Physlet-based (Physics Java Applet) illustrations and tutorials covering introductory physics.

Schneider, Scott

2007-07-21

345

Orbital Decompression in Thyroid Eye Disease  

PubMed Central

Though enlargement of the bony orbit by orbital decompression surgery has been known for about a century, surgical techniques vary all around the world mostly depending on the patient's clinical presentation but also on the institutional habits or the surgeon's skills. Ideally every surgical intervention should be tailored to the patient's specific needs. Therefore the aim of this paper is to review outcomes, hints, trends, and perspectives in orbital decompression surgery in thyroid eye disease regarding different surgical techniques. PMID:24558591

Fichter, N.; Guthoff, R. F.; Schittkowski, M. P.

2012-01-01

346

How periodic orbit bifurcations drive multiphoton ionization  

E-print Network

The multiphoton ionization of hydrogen by a strong bichromatic microwave field is a complex process prototypical for atomic control research. Periodic orbit analysis captures this complexity: Through the stability of periodic orbits we can match qualitatively the variation of experimental ionization rates with a control parameter, the relative phase between the two modes of the field. Moreover, an empirical formula reproduces quantum simulations to a high degree of accuracy. This quantitative agreement shows how short periodic orbits organize the dynamics in multiphoton ionization.

S. Huang; C. Chandre; T. Uzer

2006-12-26

347

Primary myxoid liposarcoma of the orbit.  

PubMed Central

Orbital liposarcoma is a rare and usually unsuspected neoplasm. Over a five-year period three female patients aged 22, 71, and 77 years presented with primary myxoid liposarcoma of the orbit. The management of one patient was complicated by a history of orbital decompression for suspected thyroid eye disease. The tumour infiltrates locally beyond a deceptive pseudocapsule, and surgery has to be radical to be effective. Images PMID:3228546

Lane, C M; Wright, J E; Garner, A

1988-01-01

348

Orbital Physics in Transition-Metal Oxides  

Microsoft Academic Search

An electron in a solid, that is, bound to or nearly localized on the specific atomic site, has three attributes: charge, spin, and orbital. The orbital represents the shape of the electron cloud in solid. In transition-metal oxides with anisotropic-shaped d-orbital electrons, the Coulomb interaction between the electrons (strong electron correlation effect) is of importance for understanding their metal-insulator transitions

Y. Tokura; N. Nagaosa

2000-01-01

349

Orbital subcycles for Earth remote sensing satellites  

Microsoft Academic Search

In this paper 1 review the reasons why it is desirable to place a remote-sensing satellite into an orbit which periodically repeats its path. Such exactly-repeating orbits are often used for Earth remote-sensing satellites, but the most appropriate orbit depends upon the likely application of the data. If they are to be used to study a rapidly changing phenomenon a

W. G. REES

1992-01-01

350

Operational factors affecting microgravity levels in orbit  

NASA Technical Reports Server (NTRS)

Microgravity levels desired for proposed materials processing payloads are fundamental considerations in the design of future space platforms. Disturbance sources, such as aerodynamic drag, attitude control torques, crew motion and orbital dynamics, influence the microgravity levels attainable in orbit. The nature of these effects are assessed relative to platform design parameters such as orbital altitude and configuration geometry, and examples are presented for a representative spacecraft configuration. The possible applications of control techniques to provide extremely low acceleration levels are also discussed.

Olsen, R. E.; Mockovciak, J., Jr.

1980-01-01

351

Computed tomography of the eye and orbit  

SciTech Connect

This book is the product of the evolution of computed tomography (CT) into subspecialization and the need for one source of information for the busy radiologist. The authors have succeeded in providing a readable overview of orbital CT as well as a reference book. The book is divided into seven major catagories of pathology (Neurofibromatosis, Primary Orbital Neoplasms, Secondary and Metastic Tumors of the Orbit, Vascular Disorders, Inflammatory Disease, Occular Lesions, and Trauma) after separate discussions of anatomy and technique.

Hammerschlag, S.B.; Hesselink, J.R.; Weber, A.L.

1982-01-01

352

Large capacity cryopropellant orbital storage facility  

NASA Technical Reports Server (NTRS)

A comprehensive study was performed to develop the major features of a large capacity orbital propellant storage facility for the space-based cryogenic orbital transfer vehicle. Projected propellant usage and delivery schedules can be accommodated by two orbital tank sets of 100,000 lb storage capacity, with advanced missions expected to require increased capacity. Information is given on tank pressurization schemes, propellant transfer configurations, pump specifications, the refrigeration system, and flight tests.

Schuster, J. R.

1987-01-01

353

TOPEX/Poseidon orbit acquisition maneuver design  

NASA Technical Reports Server (NTRS)

The current baseline injection orbit for the jointly sponsored NASA/CNES TOPEX/Poseidon mission is near-circular, approximately 30 km below the desired operational orbit altitude and at the operational orbit inclination. A baseline maneuver sequence to retarget from this injection orbit to the desired operational orbit has been designed based upon the expected worst-case 3-sigma injection and maneuver execution errors. The sequence requires seven maneuvers, including an initial calibration burn, and achieves the operational orbit with the desired ground track pattern in 30 days. A delay sensitivity analysis has been conducted to estimate the allowable operational delay for each maneuver without increasing the total orbit acquisition period. The baseline sequence provides back-ups for a one-revolution delay for each maneuver and one-day delay for most maneuvers. It is also shown that a higher injection orbit allows the maneuver sequence to achieve the operational orbit in 26 days under a worst-case scenario.

Bhat, Ramachandra S.

1992-01-01

354

Determination of GPS orbits to submeter accuracy  

NASA Technical Reports Server (NTRS)

Orbits for satellites of the Global Positioning System (GPS) were determined with submeter accuracy. Tests used to assess orbital accuracy include orbit comparisons from independent data sets, orbit prediction, ground baseline determination, and formal errors. One satellite tracked 8 hours each day shows rms error below 1 m even when predicted more than 3 days outside of a 1-week data arc. Differential tracking of the GPS satellites in high Earth orbit provides a powerful relative positioning capability, even when a relatively small continental U.S. fiducial tracking network is used with less than one-third of the full GPS constellation. To demonstrate this capability, baselines of up to 2000 km in North America were also determined with the GPS orbits. The 2000 km baselines show rms daily repeatability of 0.3 to 2 parts in 10 to the 8th power and agree with very long base interferometry (VLBI) solutions at the level of 1.5 parts in 10 to the 8th power. This GPS demonstration provides an opportunity to test different techniques for high-accuracy orbit determination for high Earth orbiters. The best GPS orbit strategies included data arcs of at least 1 week, process noise models for tropospheric fluctuations, estimation of GPS solar pressure coefficients, and combine processing of GPS carrier phase and pseudorange data. For data arc of 2 weeks, constrained process noise models for GPS dynamic parameters significantly improved the situation.

Bertiger, W. I.; Lichten, S. M.; Katsigris, E. C.

1988-01-01

355

GPS as an orbit determination subsystems  

NASA Technical Reports Server (NTRS)

This paper evaluates the use of Global Positioning System (GPS) receivers as a primary source of tracking data for low-Earth orbit satellites. GPS data is an alternative to using range, azimuth, elevation, and range-rate (RAER) data from the Air Force Satellite Control Network antennas, the Space Ground Link System (SGLS). This evaluation is applicable to missions such as Skipper, a joint U.S. and Russian atmosphere research mission, that will rely on a GPS receiver as a primary tracking data source. The Detachment 2, Space and Missile Systems Center's Test Support Complex (TSC) conducted the evaluation based on receiver data from the Space Test Experiment Platform Mission O (STEP-O) and Advanced Photovoltaic and Electronics Experiments (APEX) satellites. The TSC performed orbit reconstruction and prediction on the STEP-0 and APEX vehicles using GPS receiver navigation solution data, SGLS RAER data, and SGLS anglesonly (azimuth and elevation) data. For the STEP-O case, the navigation solution based orbits proved to be more accurate than SGLS RAER based orbits. For the APEX case, navigation solution based orbits proved to be less accurate than SGLS RAER based orbits for orbit prediction, and results for orbit reconstruction were inconclusive due to the lack of a precise truth orbit. After evaluating several different GPS data processing methods, the TSC concluded that using GPS navigation solution data is a viable alternative to using SGLS RAER data.

Fennessey, Richard; Roberts, Pat; Knight, Robin; Vanvolkinburg, Bart

1995-01-01

356

Orbital and epicyclic frequencies of Maclaurin spheroids  

NASA Astrophysics Data System (ADS)

We present analytical formulae for the orbital and epicyclic frequencies in orbits around Maclaurin spheroids in Newtonian gravity. The Laplace equation for the gravitational potential implies that the orbital frequency squared is the arithmetic mean of the squares of the epicyclic frequencies, ? _r^2 + ? _z^2 = 2? _o^2. The radial epicyclic frequency has a maximum at radius r=?{2}ae for spheroid ellipticities e>1/?{2}, while for e = 0.834 583 18 it vanishes at the stellar equator (at r = a). For still larger ellipticities the innermost stable circular orbit (ISCO) is separated from the surface of the spheroid by a gap and has radius rms = 1.198 203 ae. The vertical epicyclic frequency is always larger than the orbital one, and always by a factor of ?{2} in the marginally stable orbit. The presence of periastron motion, nodal precession (whose sense is the same as in retrograde orbits in the Kerr metric) and of the ISCO makes the properties of orbital motion around Maclaurin spheroids analogous to those in the Kerr metric. We find that the condition for the existence of circular orbits in test-particle motion is ? _r^2 + ? _z^2 >0, equally for the Maclaurin spheroid and for the Kerr metric.

Klu?niak, W.; Rosi?ska, D.

2013-10-01

357

Orbital Operations for Phobos and Deimos Exploration  

NASA Technical Reports Server (NTRS)

One of the deep-space human exploration activities proposed for the post-Shuttle era is a mission to one of the moons of Mars, Phobos or Deimos. There are several options available to the mission architect for operations around these bodies. These options include distant retrograde orbits (DROs), Lagrange-point orbits such as halos and Lyapunov orbits, and fixed-point stationkeeping or "hovering." These three orbit options are discussed in the context of the idealized circular restricted three body problem, full-dynamics propagations, and a concept of operations. The discussion is focused on Phobos, but all results hold for Deimos

Wallace, Mark S.; Parker, Jeffrey S.; Strange, Nathan J.; Grebow, Daniel

2012-01-01

358

A periodic table for black hole orbits  

SciTech Connect

Understanding the dynamics around rotating black holes is imperative to the success of future gravitational wave observatories. Although integrable in principle, test-particle orbits in the Kerr spacetime can also be elaborate, and while they have been studied extensively, classifying their general properties has been a challenge. This is the first in a series of papers that adopts a dynamical systems approach to the study of Kerr orbits, beginning with equatorial orbits. We define a taxonomy of orbits that hinges on a correspondence between periodic orbits and rational numbers. The taxonomy defines the entire dynamics, including aperiodic motion, since every orbit is in or near the periodic set. A remarkable implication of this periodic orbit taxonomy is that the simple precessing ellipse familiar from planetary orbits is not allowed in the strong-field regime. Instead, eccentric orbits trace out precessions of multileaf clovers in the final stages of inspiral. Furthermore, for any black hole, there is some point in the strong-field regime past which zoom-whirl behavior becomes unavoidable. Finally, we sketch the potential application of the taxonomy to problems of astrophysical interest, in particular its utility for computationally intensive gravitational wave calculations.

Levin, Janna [Department of Physics and Astronomy, Barnard College of Columbia University, 3009 Broadway, New York, New York 10027 (United States); Institute for Strings, Cosmology and Astroparticle Physics, Columbia University, New York, New York 10027 (United States); Perez-Giz, Gabe [Physics Department, Columbia University, New York, New York 10027 (United States)

2008-05-15

359

A Periodic Table for Black Hole Orbits  

E-print Network

Understanding the dynamics around rotating black holes is imperative to the success of the future gravitational wave observatories. Although integrable in principle, test particle orbits in the Kerr spacetime can also be elaborate, and while they have been studied extensively, classifying their general properties has been a challenge. This is the first in a series of papers that adopts a dynamical systems approach to the study of Kerr orbits, beginning with equatorial orbits. We define a taxonomy of orbits that hinges on a correspondence between periodic orbits and rational numbers. The taxonomy defines the entire dynamics, including aperiodic motion, since every orbit is in or near the periodic set. A remarkable implication of this periodic orbit taxonomy is that the simple precessing ellipse familiar from planetary orbits is not allowed in the strong-field regime. Instead, eccentric orbits trace out precessions of multi-leaf clovers in the final stages of inspiral. Furthermore, for any black hole, there is some point in the strong-field regime past which zoom-whirl behavior becomes unavoidable. Finally, we sketch the potential application of the taxonomy to problems of astrophysical interest, in particular its utility for computationally intensive gravitational wave calculations.

Janna Levin; Gabe Perez-Giz

2008-02-04

360

NASA Orbiter Extended Nose Landing Gear  

NASA Technical Reports Server (NTRS)

This paper discusses the design, development, test, and evaluation of a prototype Extended Nose Landing Gear (ENLG) for NASA's Space Shuttle orbiters. The ENLG is a proposed orbiter modification developed in-house at NASA's Johnson Space Center (JSC) by a joint government/industry team. It increases the orbiter's nose landing gear (NLG) length, thereby changing the vehicle's angle of attack during rollout, which lowers the aerodynamic forces on the vehicle. This, in combination with a dynamic elevon change, will lower the loads on the orbiter's main landing gear (MLG). The extension is accomplished by adding a telescoping section to the current NLG strut that will be pneumatically extended during NLG deployment.

King, Steven R.; Jensen, Scott A.; Hansen, Christopher P.

1999-01-01

361

Orbit stability of the ALS storage ring  

SciTech Connect

The Advanced Light Source (ALS) storage ring, a synchrotron light source of the third generation, is specified to maintain its electron orbit stable within one tenth of the rms beam size. In the absence of a dedicated orbit feed-back system, several orbit-distorting effects were investigated, aided by a new interactive simulation tool, the code TRACY V. The effort has led to a better understanding of the behavior of a variety of accelerator subsystems and in consequence produced a substantial improvement in day-to-day orbit stability.

Keller, R.; Nishimura, H.; Biocca, A. [and others

1997-05-01

362

On-Orbit Compressor Technology Program  

NASA Technical Reports Server (NTRS)

A synopsis of the On-Orbit Compressor Technology Program is presented. The objective is the exploration of compressor technology applicable for use by the Space Station Fluid Management System, Space Station Propulsion System, and related on-orbit fluid transfer systems. The approach is to extend the current state-of-the-art in natural gas compressor technology to the unique requirements of high-pressure, low-flow, small, light, and low-power devices for on-orbit applications. This technology is adapted to seven on-orbit conceptual designs and one prototype is developed and tested.

Deffenbaugh, Danny M.; Svedeman, Steven J.; Schroeder, Edgar C.; Gerlach, C. Richard

1990-01-01

363

Nebraska Astronomy Applet Project: Planetary Orbit Simulator  

NSDL National Science Digital Library

This simulation illustrates the physics of planetary orbits. The user can control the size and orbital path of the orbit. Each of Kepler's three laws and aspects of Newton's Law are each demonstrated. Velocity and acceleration vectors can be displayed, as well as the axes of the orbit. Instructor resources are available including student manuals, assessment materials, and a list of the assumptions used. This resource is part of a larger collection of online labs for introductory astronomy.See Related Materials for a link to the full collection.

Lee, Kevin M.

2007-12-20

364

The NOVA-2 postlaunch orbit adjustment process  

NASA Astrophysics Data System (ADS)

The NOVA-2 satellite was the last of three `drag free' spacecraft to be placed into the Transit Navigation Systems's constellation of satellites. After its launch from Vandenburg Air Force Base into an initial 510 x 170 nmi near poar orbit, an intensive two-week operations schedule was implemented to : raise the orbit approximately 450 nmi to within .015 sec of desired period, trim eccentricity to within .003, trim inclination to within .006 degrees of requirement, freeze the phase of the spacecraft in orbit relative to the other two `drag free' satellites, dump extra fuel by deliberately fual wasting burns, and transition the spacecraft from a slow spin mode to gravity gradient. This paper will briefly discuss the concept of a `drag free' satellite, the selection of the orbit plane in the constellations, and the derivation of the required final orbit parameters. The paper will also discuss peripheral support needed to assist the OATS (Orbit Adjust and Transfer System) ground software, including attitude determination and maneuvers, orbit determination, and orbit prediction through the burns. However, the specific focus of this paper is on the design and execution of the nine OATS burns that accomplished the orbital maneuvers.

Heyler, Gene A.

365

Demonstration of Electrostatic Orbits in Weightlessness  

NASA Astrophysics Data System (ADS)

In August 2006, a team of students from Rhodes College performed an experiment in microgravity aboard NASA’s specialized C-9B aircraft known as the “Weightless Wonder.” The goal of the experiment was to establish an orbit between two electrically charged spheres. The similar forms of Newton’s Law of Gravitation and Coulomb’s Law suggest that such electrostatic orbits are possible. However, to our knowledge, an electrostatic orbit has not previously been demonstrated. This presentation will describe our experiment and show video footage of the electrostatic orbits that we achieved in weightlessness. Professor Brent Hoffmeister is the AAPT sponsor.

Janeski, John; Andring, K.; Banerjee, S.; Campbell, D.; Keedy, D.; Hoffmeister, B.; Quinn, S.

2006-12-01

366

Numerical Mean Element Orbital Analysis with Morbiter  

NASA Technical Reports Server (NTRS)

The Morbiter software numerically averages an osculating orbit s equations of motion (EOM) to arrive at the mean orbit s EOMs, which are then numerically propagated to obtain the long-term orbital ephemerides. The long-term evolution characteristics, and stability, of an orbit are best characterized using a mean element propagation of the perturbed, two-body variational equations of motion. The average process eliminates short period terms, leaving only secular and long period effects. Doing this avoids the Fourier series expansions and truncations required by the traditional analytic methods.

Ely, Todd A.

2010-01-01

367

Payload/orbiter contamination control assessment support  

NASA Technical Reports Server (NTRS)

The development and use is described of a basic contamination mathematical model of the shuttle orbiter which incorporates specific shuttle orbiter configurations and contamination sources. These configurations and sources were evaluated with respect to known shuttle orbiter operational surface characteristics and specific lines-of-sight which encompass the majority of viewing requirements for shuttle payloads. The results of these evaluations are presented as summary tables for each major source. In addition, contamination minimization studies were conducted and recommendations are made, where applicable, to support the shuttle orbiter design and operational planning for those sources which were identified to present a significant contamination threat.

Rantanen, R. O.; Ress, E. B.

1975-01-01

368

Aerodynamic lift effect on satellite orbits  

NASA Technical Reports Server (NTRS)

Numerical quadrature is employed to obtain orbit perturbation results from the general perturbation equations. Both aerodynamic lift and drag forces are included in the analysis of the satellite orbit. An exponential atmosphere with and without atmospheric rotation is used. A comparison is made of the perturbations which are caused by atmospheric rotation with those caused by satellite aerodynamic effects. Results indicate that aerodynamic lift effects on the semi-major axis and orbit inclination can be of the same order as the effects of atmosphere rotation depending upon the orientation of the lift vector. The results reveal the importance of including aerodynamic lift effects in orbit perturbation analysis.

Karr, G. R.; Cleland, J. G.; Devries, L. L.

1975-01-01

369

A remotely controlled orbiting retriever  

NASA Technical Reports Server (NTRS)

A preliminary design effort was recently carried out to investigate methods of removing a certain class of space objects from Shuttle type orbits. Specifically, expired satellites, upper stages, and other objects of potential danger to the Shuttle are the targets of the study. The Trash Remover and Satellite Hauler (TRASH-1) design effort was broken into several disciplines: mission analysis, systems engineering, dynamics and control, power, thermal, and propulsion. A basic requirements is that TRASH-1 go up in the Shuttle. It must be reusable and capable of disposing of more than one item per mission for cost effectiveness. These requirements imply TRASH-1 should use current technology, be modular in design, and be relatively maneuverable. In order to maximize utility, it should be able to both capture and deorbit objects. The design was a basic bus with attachable modules which can either capture or deorbit, depending on the module.

Kaplan, M. H.

1985-01-01

370

Free space laser communication experiments from Earth to the Lunar Reconnaissance Orbiter in lunar orbit  

E-print Network

Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. ...

Sun, Xiaoli

371

Measurements of the STS orbiter's angular stability during in-orbit operations  

NASA Technical Reports Server (NTRS)

We report on measurements of the angular stability, commonly called 'jitter', of the STS Orbiter during normal operations in space. Measurements were carried out by measuring optically the Orbiter's roll and pitch orientation relative to the solar vector as the orbiter was held in a -Z(sub 0) solar inertial orientation (orbiter bay oriented toward the Sun). We also report observations of an interesting perturbation to the orbiter's orientation noted by the crew during the STS-60 mission. These data may be useful in analyzing the in-orbit response of the Orbiter to thruster firings and other applied torques, and may aid in the planning of future experiments that require fine-pointed operations by the orbiter.

Neupert, Werner M.; Epstein, Gabriel L.; Houston, James; Zarechnak, Andrew

1995-01-01

372

GOCE Satellite Orbit in a Computational Aspect  

NASA Astrophysics Data System (ADS)

The presented work plays an important role in research of possibility of the Gravity Field and Steady-State Ocean Circulation Explorer Mission (GOCE) satellite orbit improvement using a combination of satellite to satellite tracking high-low (SST- hl) observations and gravity gradient tensor (GGT) measurements. The orbit improvement process will be started from a computed orbit, which should be close to a reference ("true") orbit as much as possible. To realize this objective, various variants of GOCE orbit were generated by means of the Torun Orbit Processor (TOP) software package. The TOP software is based on the Cowell 8th order numerical integration method. This package computes a satellite orbit in the field of gravitational and non-gravitational forces (including the relativistic and empirical accelerations). The three sets of 1-day orbital arcs were computed using selected geopotential models and additional accelerations generated by the Moon, the Sun, the planets, the Earth and ocean tides, the relativity effects. Selected gravity field models include, among other things, the recent models from the GOCE mission and the models such as EIGEN-6S, EIGEN-5S, EIGEN-51C, ITG-GRACE2010S, EGM2008, EGM96. Each set of 1-day orbital arcs corresponds to the GOCE orbit for arbitrary chosen date. The obtained orbits were compared to the GOCE reference orbits (Precise Science Orbits of the GOCE satellite delivered by the European Space Agency) using the root mean squares (RMS) of the differences between the satellite positions in the computed orbits and in the reference ones. These RMS values are a measure of performance of selected geopotential models in terms of GOCE orbit computation. The RMS values are given for the truncated and whole geopotential models. For the three variants with the best fit to the reference orbits, the empirical acceleration models were added to the satellite motion model. It allowed for further improving the fitting of computed orbits to the reference orbits. A linear and non-linear model of empirical accelerations was used. After using the non-linear model, the RMS values were reduced by the factor from about 2 to 3 compared with the linear model. A general form of the non-linear model of empirical accelerations is shown in this work. This model can be scaled to a given set of dynamical data for orbit determination by estimating of 192 parameters. The comparison between the computed orbits and the reference ones was performed with respect to the inertial reference frame (IRF) at J2000.0 epoch. Thus, the given GOCE reference orbits were transformed from ITRF2005 reference frame into IRF frame. It is shown that the velocity components of GOCE reference orbits must be transformed into IRF frame using the full rotation vector of the Earth. In such a case RMS values reach a level of meters.

Bobojc, Andrzej; Drozyner, Andrzej

2013-04-01

373

Spin-orbit coupling: A unified theory of orbital and rotational resonances  

Microsoft Academic Search

The dynamics of the spin-orbit interaction of a sphereM8 and a rotating asymmetrical rigid bodyMa are examined. No restrictions are imposed on the masses, on the orientation of the rotation axis to the orbit plane, or on the orbit eccentricity. The zonal potential harmonics ofMa induce a precession of the spin axis as well as a precession of the orbit

Patrick J. Hamill; Leon Blitzer

1974-01-01

374

Orbital Dynamics of Low-Earth Orbit Laser-Propelled Space Vehicles  

SciTech Connect

Trajectories applicable to laser-propelled space vehicles with a laser station in low-Earth orbit are investigated. Laser vehicles are initially located in the vicinity of the Earth-orbiting laser station in low-earth orbit at an altitude of several hundreds kilometers, and are accelerated by laser beaming from the laser station. The laser-propelled vehicles start from low-earth orbit and finally escape from the Earth gravity well, enabling interplanetary trajectories and planetary exploration.

Yamakawa, Hiroshi [Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 (Japan); Funaki, Ikkoh [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara, Kanagawa, 229-8510 (Japan); Komurasaki, Kimiya [Department of Advanced Energy, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba, 277-8561 (Japan)

2008-04-28

375

Orbits Close to Asteroid 4769 Castalia  

NASA Technical Reports Server (NTRS)

We use a radar-derived physical model of 4769 Castalia (1989 PB) to investigate close orbit dynamics around that kilometer- sized, uniformly rotating asteroid. Our methods of analysis provide a basis for systematic studies of particle dynamics close to any uniformly rotating asteroid. We establish that a Jacobi integral exists for particles orbiting this asteroid, examine the attendant zero-velocity surfaces, find families of periodic orbits, and determine their stability. All synchronous orbits and direct orbits within approx. 3 mean radii of Castalia are unstable and are subject to impact or escape from Castalia. Retrograde orbits are mostly stable and allow particles to orbit close to the asteroid surface. We derive a model which allows us to predict the escape conditions of a particle in orbit about Castalia and the (temporary) capture conditions for a hyperbolic interloper. Orbits within 1.5 km of Castalia are subject to immediate ejection from the system. Hyperbolic orbits with a V(sub infinity) less than 0.4 m/sec can potentially be captured by Castalia if their periapsis radius Is within approx. 2 km. For Castalia this capture region is small, but the results also apply to larger asteroids whose capture regions would also be larger. We determine bounds on ejecta speeds which either ensure ejecta escape or re-impact as functions of location on Castalia's surface. The speeds that ensure escape range from 0.28 to 0.84 m/sec and the speeds that ensure re-impact range from 0 to 0.18 m/sec. Speeds between these two bounds lead either to escape, re-impact, or potentially finite-time stable orbits. We develop a simple criterion which can establish whether a particle could have been ejected from the asteroid in the past and if it will impact the surface in the future.

Scheeres, D. J.; Ostro, S. J.; Hudson, R. S.; Werner, R. A.

1996-01-01

376

Admissible orbits in the Oort cloud and velocities on such orbits  

Microsoft Academic Search

In this paper we deal with determinations of: admissible orbits and ranges of orbital velocity in the cloud, extremal velocities at the distance r from the Sun. Moreover, in velocity space we consider the Or region in which there are located tips of velocity vectors for comets moving on admissible orbits.

Richard A. Serafin; A. Mickiewicz

1987-01-01

377

Orbital socket contracture: a complication of inflammatory orbital disease in patients with Wegener’s granulomatosis  

Microsoft Academic Search

Aim: To describe the clinical characteristics of orbital socket contracture in patients with Wegener’s granulomatosis (WG).Methods: A retrospective cohort study The medical records of 256 patients with WG examined at the National Institutes of Health from 1967 to 2004 were reviewed to identify patients with orbital socket contracture. Details of the orbital disease including Hertel exophthalmometry readings, radiological findings, and

C Talar-Williams; M C Sneller; C A Langford; J A Smith; T A Cox; M R Robinson

2005-01-01

378

Ionospheric refraction effects on orbit determination using the orbit determination error analysis system  

Microsoft Academic Search

The influence of ionospheric refraction on orbit determination was studied through the use of the Orbit Determination Error Analysis System (ODEAS). The results of a study of the orbital state estimate errors due to the ionospheric refraction corrections, particularly for measurements involving spacecraft-to-spacecraft tracking links, are presented. In current operational practice at the Goddard Space Flight Center (GSFC) Flight Dynamics

C. P. Yee; D. A. Kelbel; T. Lee; J. B. Dunham; G. D. Mistretta

1990-01-01

379

Blurry vision after orbital decompression surgery.  

PubMed

Pathologic myopia may be associated with abnormal vitreomacular adhesions that can portend a higher risk of retinal detachment. The authors report a case of rhegmatogenous retinal detachment with a complex macular tear after orbital decompression surgery in a patient with pathologic myopia. This case highlights the importance of retinal detachment in the setting of orbital decompression. PMID:24806699

Elshatory, Yasser; Shah, Vinay A; Hildebrand, P Lloyd

2014-01-01

380

Periodic Orbits of Coupled Oscillators Near Resonance  

E-print Network

Periodic Orbits of Coupled Oscillators Near Resonance Carmen Chicone Department of Mathematics of synchronization of two detuned and weakly inductively coupled van der Pol oscillators. 1 Introduction Coupled of periodic orbits for coupled oscillators in case the unperturbed oscillators are in resonance. To orient

Chicone, Carmen

381

Orbital Meningocele Presenting as Periorbital Cellulitis  

Microsoft Academic Search

A case of orbital meningocele in a 15-day-old infant presenting as periorbital cellulitis, followed by meningitis, is described. Unlike other cases with the same anomaly, signs were not noted in the involved eye, neither before the cellulitis nor after recovery following antibiotic treatment. Preoperative diagnosis was confirmed by tomography of the orbit. On operation a bony defect was found in

Z. Weizman; A. Tenembaum; M. Perlman; A. Sahar

1981-01-01

382

Interagency Report on Orbital Debris, 1995  

NASA Technical Reports Server (NTRS)

This 1995 report updates the findings and recommendations of the 1989 report and reflects the authors' progress in understanding and managing the orbital debris environment. It provides an up-to-date portrait of their measurement, modeling, and mitigation efforts; and a set of recommendations outlining specific steps they should pursue, both domestically and internationally, to minimize the potential hazard posed by orbital debris.

1995-01-01

383

On-Orbit Propulsion OMS/RCS  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the Space Shuttle's On-Orbit Propulsion systems: the Orbital Maneuvering System (OMS) and the Reaction Control System (RCS). The functions of each of the systems is described, and the diagrams of the systems are presented. The OMS/RCS thruster is detailed and a trade study comparison of non-toxic propellants is presented.

Hurlbert, Eric A.

2001-01-01

384

Midline granuloma presenting as orbital cellulitis  

Microsoft Academic Search

? Background: Lethal midline granuloma usually presents with rhinorrhoea and redness of the skin above the nose. Early ocular symptoms are very rare. We here describe a patient who presented with acute orbital cellulitis. ? Patient: A 73-year-old woman had a 24-h history of severe pain around her left eye. We saw the typical clinical picture of orbital cellulitis. A

Jiirg Heinrieh Meyer; Bernhard Scharf; Jiirgen Gerling

1996-01-01

385

NORAD TLE Conversion from Osculating Orbital Element  

Microsoft Academic Search

The NORAD type Two Line Element (TLE) was obtained from the osculating orbital elements by an iterative approximation procedure. The mathematical model was presented and computer program was developed for the conversion. The osculating orbital elements of the KOMPSAT-1 were converted into the NORAD TLE. Then the effect of the SGP4 atmospheric drag coefficient (B*) was analyzed by comparison of

Byoung-Sun Lee

2002-01-01

386

Near Earth Objects Program: Orbit Diagrams  

NSDL National Science Digital Library

This page provides access to diagrams of the orbits of a very large number of objects in the asteroid belt as well as comets that cross Earth's orbit. The collection is searchable by object name or designation and users can also browse through an extensive list of potentially hazardous asteroids.

NASA JPL Near Earth Object Program

387

Orbit: an optimizing compiler for scheme  

Microsoft Academic Search

Orbit was an optimizing compiler for T, a dialect of Scheme. Its aggressive use of CPS conversion, novel closure representations, and efficient code generation strategies made it the best compiler for a Scheme dialect at the time and for many years to come. The design of T and Orbit directly spawned six PhD theses and one Masters thesis, and influenced

David Kranz; Richard Kelsey; Jonathan Rees; Paul Hudak; James Philbin; Norman Adams

2004-01-01

388

Local and global behavior near homoclinic orbits  

Microsoft Academic Search

We study the local behavior of systems near homoclinic orbits to stationary points of saddle-focus type. We explicitly describe how a periodic orbit approaches homoclinicity and, with the help of numerical examples, discuss how these results relate to global patterns of bifurcations.

Paul Glendinning; Colin Sparrow

1984-01-01

389

Students' Understanding of Orbitals: A Survey.  

ERIC Educational Resources Information Center

The study of chemistry includes many abstract concepts that students may find difficult to understand. A fundamental yet troublesome part of introductory chemistry courses is the topic of electron configuration and specifically quantum-mechanical orbitals. In an effort to examine the way students internalize the concept of atomic orbitals and how…

MacKinnon, Gregory R.

390

Orbit mechanics of deep space probes  

Microsoft Academic Search

Emphasized are orbits with high inclinations from the earth-moon orbital plane, with initial major axes oriented perpendicularly or inclined to the axis of syzygies and with period near that of the moon. The relation of this problem to the restricted problem of three and four bodies is discussed, showing the effects of luni-solar ephemerides versus the 'circular problem'. Various modifications

J. J. F. Liu; J. Segrest; V. Szebehely

1986-01-01

391

Inverse-Square Orbits: A Geometric Approach.  

ERIC Educational Resources Information Center

Presents a derivation of Kepler's first law of planetary motion from Newtonian principles. Analogus derivations of the hyperbolic and parabolic orbits of nonreturning comets and the hyperbolic orbit for a particle in a repulsive inverse-square field are also presented. (HM)

Rainwater, James C.; Weinstock, Robert

1979-01-01

392

Eta Carinae: Orientation of The Orbital Plane  

Microsoft Academic Search

Evidence continues to build that Eta Carinae is a massive binary system with a hidden hot companion in a highly elliptical orbit. We present imaging and spectroscopic evidence that provide clues to the orientation of the orbital plane. The circumstellar ejecta, known as the Homunculus and Little Homunculus, are hourglass-shaped structures, one encapsulated within the other, tilted at about 45

T. R. Gull; K. E. Nielsen; S. Ivarsson; M. F. Corcoran; E. Verner; J. D. Hillier

2005-01-01

393

Project Management in NASA Mars Climate Orbiter  

E-print Network

Report on Project Management in NASA by the Mars Climate Orbiter Mishap Investigation Board March Acknowledgements 5 Executive Summary 6 1. Introduction 10 2. The Mars Climate Orbiter Mission: Observations and Lessons Learned 15 3. A New Vision for NASA Programs and Projects 24 4. NASA's Current Program

Rhoads, James

394

Periodic orbits in scattering from elastic voids  

E-print Network

The scattering determinant for the scattering of waves from several obstacles is considered in the case of elastic solids with voids. The multi-scattering determinant displays contributions from periodic ray-splitting orbits. A discussion of the weights of such orbits is presented.

Niels Sondergaard; Predrag Cvitanovic; Andreas Wirzba

2006-03-22

395

Space shuttle orbiter test flight series  

NASA Technical Reports Server (NTRS)

The proposed studies on the space shuttle orbiter test taxi runs and captive flight tests were set forth. The orbiter test flights, the approach and landing tests (ALT), and the ground vibration tests were cited. Free flight plans, the space shuttle ALT crews, and 747 carrier aircraft crew were considered.

Garrett, D.; Gordon, R.; Jackson, R. B.

1977-01-01

396

Spin-orbit torques in action  

NASA Astrophysics Data System (ADS)

The spin-orbit interaction can generate torques that act on the magnetization of a ferromagnet. Here we examine recent experimental insights into spin-orbit torques, which have generated competing explanations and differing opinions over their potential application in memory devices.

Brataas, Arne; Hals, Kjetil M. D.

2014-02-01

397

Spacecraft external heating variations in orbit  

NASA Technical Reports Server (NTRS)

The results of an evaluation of variations in on-orbit external heating of spacecraft surfaces are presented. The analyzed time-varying components are the direct solar, the latitude-dependent shortwave reflected, and the latitude-dependent longwave planetary-emitted radiation. Differences in instantaneous heating rates at a given latitude among the different model environments are found to be much larger than are differences in orbital mean heating rates. The discrepancies are found to increase with the orbit inclination angle. The ratio of Northern Hemisphere winter-to-summer orbital mean heating rates for a nadir-facing node is near unity and shows only a slight dependence on large variations in node absorptance. Mean orbital albedo and emission values for low-inclination orbits are found to differ significantly from global values obtained in meteorological studies. Algorithms relating mean orbital albedos and emissions to orbit inclination are developed. The relative importance of more realistic nondiffuse over diffuse reflections is evaluated for spacecraft heating and found to be negligible. The sun-spacecraft-earth angular configuration is such that, for reception of the peak intensities in the nondiffuse reflectance angular distribution, the albedo heating rate is more than adequately suppressed by an extremely small view factor from the spacecraft to the sunlit 'crescent' earth.

Leffler, J. M.

1987-01-01

398

HORSESHOE PERIODIC ORBITS FOR SATURN COORBITAL SATELLITES  

E-print Network

HORSESHOE PERIODIC ORBITS FOR SATURN COORBITAL SATELLITES Jaume Llibre and Merc`e Oll'e Dept. Matem conclude that there exist stable horseshoe periodic orbits which fit with the motion of Saturn coorbital­ stricted problem. 1. Introduction In 1981 the successful Voyager flights to Saturn confirmed the existence

Politècnica de Catalunya, Universitat

399

Demonstration of Electrostatic Orbits in Weightlessness  

Microsoft Academic Search

In August 2006, a team of students from Rhodes College performed an experiment in microgravity aboard NASA's specialized C-9B aircraft known as the ``Weightless Wonder.'' The goal of the experiment was to establish an orbit between two electrically charged spheres. The similar forms of Newton's Law of Gravitation and Coulomb's Law suggest that such electrostatic orbits are possible. However, to

John Janeski; K. Andring; S. Banerjee; D. Campbell; D. Keedy; B. Hoffmeister; S. Quinn

2006-01-01

400

A Catalog of Selected Viking Orbiter Images  

NASA Technical Reports Server (NTRS)

This collection of Viking Orbiter photomosaics is designed to facilitate identification and location of the various pictures with respect to the surface of Mars. Only a representative set of the nearly 50,000 images taken by the two Viking Orbiters, and computer-processed prior to December 1978, are contained in the mosaics and in the picture listings.

Turner, R. L.; Carroll, R. D.

1983-01-01

401

Orbital insolation, ice volume, and greenhouse gases  

Microsoft Academic Search

The SPECMAP models of orbital-scale climate change (Imbrie et al., Paleoceanography 7 (1992) 701, Paleoceanography 8 (1993) 699) are the most comprehensive to date: all major climatic observations were analyzed within the framework of the three orbital signals. Subsequently, tuning of signals in Vostok ice to insolation forcing has fixed the timing of greenhouse-gas changes closely enough to permit an

William F. Ruddiman

2003-01-01

402

Endoscopic orbital decompression for Graves’ orbitopathy  

PubMed Central

Aim: To study the efficacy of endonasal endoscopic orbital decompression in cases of Graves’ orbitopathy. Material and Methods: A total of 24 orbits in 12 patients underwent endoscopic orbital decompression for graves orbitopathy in the period between October 2002 and December 2010. Indications for surgery included proptosis, corneal exposure, keratitis, and compressive optic neuropathy. Decompression was accomplished by the removal of the medial and part of inferior wall of the orbit and slitting of the orbital periosteum. Pre and postoperative exophthalmometry measurements and visual acuity were recorded and compared. Results: A mean orbital regression of 3.70 mm was noted following endoscopic decompression. The visual acuity improved significantly in one of two eyes decompressed for failing visual acuity secondary to optic nerve compression. Transient diplopia was invariable following surgery but resolved over the next 8 weeks. One case manifested unilateral frontal sinus obstruction symptoms 4 months postoperatively and responded to medical therapy. Conclusion: Endonasal endoscopic orbital decompression provides for an effective, safe, and minimally invasive treatment for proptosis and visual loss of Graves Orbitopathy. Long-term problems with diplopia were not noted in the endonasal endoscopic approach for orbital decompression. PMID:23776900

Lal, Priti; Thakar, Alok; Tandon, Nikhil

2013-01-01

403

GRAVITATIONAL IONIZATION: PERIODIC ORBITS OF BINARY SYSTEMS  

E-print Network

GRAVITATIONAL IONIZATION: PERIODIC ORBITS OF BINARY SYSTEMS PERTURBED BY GRAVITATIONAL RADIATION C of a Newtonian binary system by an in- cident gravitational wave is discussed in connection with the issue of gravitational ionization. The periodic orbits of the planar tidal equation are investigated and the conditions

Chicone, Carmen

404

GRAVITATIONAL IONIZATION: PERIODIC ORBITS OF BINARY SYSTEMS  

E-print Network

GRAVITATIONAL IONIZATION: PERIODIC ORBITS OF BINARY SYSTEMS PERTURBED BY GRAVITATIONAL RADIATION C by an incident gravitational wave is discussed in connection with the issue of gravitational ionization are presented. The possibility of ionization of a Keplerian orbit via gravitational radiation is discussed. 1

405

Posttraumatic Orbital Emphysema: A Numerical Model  

PubMed Central

Orbital emphysema is a common symptom accompanying orbital fracture. The pathomechanism is still not recognized and the usually assumed cause, elevated pressure in the upper airways connected with sneezing or coughing, does not always contribute to the occurrence of this type of fracture. Observations based on the finite model (simulating blowout type fracture) of the deformations of the inferior orbital wall after a strike in its lower rim. Authors created a computer numeric model of the orbit with specified features—thickness and resilience modulus. During simulation an evenly spread 14400?N force was applied to the nodular points in the inferior rim (the maximal value not causing cracking of the outer rim, but only ruptures in the inferior wall). The observation was made from 1 · 10?3 to 1 · 10?2 second after a strike. Right after a strike dislocations of the inferior orbital wall toward the maxillary sinus were observed. Afterwards a retrograde wave of the dislocation of the inferior wall toward the orbit was noticed. Overall dislocation amplitude reached about 6?mm. Based on a numeric model of the orbit submitted to a strike in the inferior wall an existence of a retrograde shock wave causing orbital emphysema has been found. PMID:25309749

Skorek, Andrzej; K?osowski, Pawe?; Plichta, ?ukasz; Zmuda Trzebiatowski, Marcin; Lemski, Pawe?

2014-01-01

406

Orbital express space operations architecture program  

Microsoft Academic Search

The goal of the Orbital Express Space Operations Architecture program is to validate the technical feasibility of robotic, autonomous on-orbit refueling and reconfiguration of satellites to support a broad range of future U.S. national security and commercial space programs. Refueling satellites will enable frequent maneuvers to improve coverage, change arrival times to counter denial and deception, and improve survivability, as

James Shoemaker; Melissa Wright

2004-01-01

407

Orbital express space operations architecture program  

Microsoft Academic Search

The goal of the Orbital Express Space Operations Architecture program is to validate the technical feasibility of robotic, autonomous on-orbit refueling and reconfiguration of satellites to support a broad range of future U.S. national security and commercial space programs. Refueling satellites will enable frequent maneuvers to improve coverage, change arrival times to counter denial and deception, and improve survivability, as

James Shoemaker; Melissa Wright

2003-01-01

408

Approximating Stellar Orbits: Improving on Epicycle Theory  

E-print Network

Already slightly eccentric orbits, such as those occupied by many old stars in the Galactic disk, are not well approximated by Lindblad's epicycle theory. Here, alternative approximations for flat orbits in axisymmetric stellar systems are derived and compared to results from numeric integrations. All of these approximations are more accurate than Lindblad's classical theory. I also present approximate, but canonical, maps from ordinary phase-space coordinates to a set of action-angle variables. Unfortunately, the most accurate orbit approximation leads to non-analytical R(t). However, from this approximation simple and yet very accurate estimates can be derived for the peri- and apo-centers, frequencies, and actions integrals of galactic orbits, even for high eccentricities. Moreover, further approximating this approximation allows for an analytical R(t) and still an accurate approximation to galactic orbits, even with high eccentricities.

Walter Dehnen

1999-06-04

409

Orbiting and Colliding Galaxies 3D Model  

NSDL National Science Digital Library

The Orbiting and Colliding Galaxies 3D Model is a three-dimensional extension of the Alar and Juri Toomres' 1972 supercomputer model of colliding galaxies. This model assumes that galactic centers are point masses and the orbiting stars do not interact with each other (the galactic cores interact with each other and the individual stars). Unlike the Toomres' model (and the Colliding Galaxies model by Christian and Lim), both galactic cores begin with a compliment of stars orbiting their respective cores. These stars start in a 3-D circular orbit about the center of each galaxy in one plane. When the two galaxies pass each other they produce the long spiraling tails. The Orbiting and Colliding Galaxies Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_comp_phys_colliding_galaxies3d.jar file will run the program if Java is installed.

Mitchell, Robbie

2011-06-15

410

Asteroids in Retrograde Orbits: Interesting Cases  

NASA Astrophysics Data System (ADS)

We present the most interesting examples of the orbital evolution of asteroids in retrograde orbits (i > 90°). First, we used the latest observational data to determine nominal and averaged orbital elements of these objects. Next, the equations of motion of these asteroids were integrated backward 1 My, taking into account the propagation of observational errors. We used so-called 'cloning' procedure to reproduce the reliability of initial data. We obtained some possible scenarios of the orbit inversion in the past, what is often caused by the long-term influence of outer planets. For two most interesting cases (Apollo and Amor type) we did additional calculations: 100 My in the future. Additionally, we investigated the potential influence of Yarkovski/YORP effects on the long-time orbital evolution.

Kankiewicz, Pawe?; W?odarczyk, Ireneusz

2014-12-01

411

Methods of orbit correction system optimization  

SciTech Connect

Extracting optimal performance out of an orbit correction system is an important component of accelerator design and evaluation. The question of effectiveness vs. economy, however, is not always easily tractable. This is especially true in cases where betatron function magnitude and phase advance do not have smooth or periodic dependencies on the physical distance. In this report a program is presented using linear algebraic techniques to address this problem. A systematic recipe is given, supported with quantitative criteria, for arriving at an orbit correction system design with the optimal balance between performance and economy. The orbit referred to in this context can be generalized to include angle, path length, orbit effects on the optical transfer matrix, and simultaneous effects on multiple pass orbits.

Chao, Yu-Chiu

1997-08-01

412

The Solar Poynting-Robertson Effect On Particles Orbiting Solar System Bodies: Circular Orbits  

NASA Technical Reports Server (NTRS)

The Poynting-Robertson effect from sunlight impinging directly on a particle which orbits a Solar System body (planet, asteroid, comet) is considered from the Sun's rest frame. There appear to be no significant first-order terms in V(sub b)/c for circular orbits, where V(sub b) is the body's speed in its orbit about the Sun and c is the speed of light, when the particle's orbital semimajor axis is much smaller than the body's orbital semimajor axis about the Sun as is mainly the case in the Solar System.

Rubincam, David P.

2013-01-01

413

Numerical experiments on planetary orbits in double stars  

Microsoft Academic Search

This is a numerical study of orbits in the elliptic restricted three-body problem concerning the dependence of the critical orbits on the eccentricity of the primaries. They are defined as being the separatrix between stable and unstable single periodic orbits. As our results are adapted to the existence of planetary orbits in double stars we concentrated first on the P-orbits

R. Dvorak

1984-01-01

414

Evolution of Giant Planets on Eccentric Orbits  

NASA Astrophysics Data System (ADS)

We have investigated the interaction of an eccentric orbit planet with a circumstellar disk by means of high-resolution hydrodynamical simulations. We have focused on the planet's mass range from one to a few Jupiter-masses. This study aims at characterizing the mass accretion and the orbital eccentricity evolution of giant planets. We find that the accretion rate depends on the orbital eccentricity of the protoplanet and that the accretion is pulsed on the orbital period, as found in simulations of binary star systems. Most of the mass is accreted while the protoplanet is around the apocenter position. A Jupiter-mass planet with orbital eccentricity e=0.3 accretes at a rate that is 33% higher than the accretion rate of a Jupiter-mass planet on a circular orbit. A 3 Jupiter-mass planet with e=0.1 is able to accrete, during one orbital period, 40% more mass than a similar size planet on a circular orbit. Simulations also indicate that a massive planet tend to sustain eccentricity growth in the disk, even with the planet revolving on a circular orbit, as already found for binary star systems. The interaction of the massive planet with the eccentric disk can then lead to the growth of the planet's orbital eccentricity. These results are consistent with observations of extrasolar planets. In fact, the most massive planets exhibit higher eccentricities than lower mass planets do. GD is supported by the UK Astrophysical Fluids Facility (UKAFF) through a UKAFF Fellowship. SL acknowledges support from NASA grant NNG04GG50G.

D'Angelo, G.; Lubow, S. H.; Bate, M. R.

2005-12-01

415

ORBITS AROUND BLACK HOLES IN TRIAXIAL NUCLEI  

SciTech Connect

We discuss the properties of orbits within the influence sphere of a supermassive black hole (BH), in the case that the surrounding star cluster is non-axisymmetric. There are four major orbit families; one of these, the pyramid orbits, have the interesting property that they can approach arbitrarily closely to the BH. We derive the orbit-averaged equations of motion and show that in the limit of weak triaxiality, the pyramid orbits are integrable: the motion consists of a two-dimensional libration of the major axis of the orbit about the short axis of the triaxial figure, with eccentricity varying as a function of the two orientation angles and reaching unity at the corners. Because pyramid orbits occupy the lowest angular momentum regions of phase space, they compete with collisional loss cone repopulation and with resonant relaxation (RR) in supplying matter to BHs. General relativistic advance of the periapse dominates the precession for sufficiently eccentric orbits, and we show that relativity imposes an upper limit to the eccentricity: roughly the value at which the relativistic precession time is equal to the time for torques to change the angular momentum. We argue that this upper limit to the eccentricity should also apply to evolution driven by RR, with potentially important consequences for the rate of extreme-mass-ratio inspirals in low-luminosity galaxies. In giant galaxies, we show that capture of stars on pyramid orbits can dominate the feeding of BHs, at least until such a time as the pyramid orbits are depleted; however this time can be of order a Hubble time.

Merritt, David [Department of Physics and Center for Computational Relativity and Gravitation, Rochester Institute of Technology, Rochester, NY 14623 (United States); Vasiliev, Eugene, E-mail: merritt@astro.rit.edu, E-mail: eugvas@lpi.ru [Lebedev Physical Institute, Leninsky prospekt 53, Moscow (Russian Federation)

2011-01-10

416

Projected seniority-two orbital optimization of the antisymmetric product of one-reference orbital geminal  

NASA Astrophysics Data System (ADS)

We present a new, non-variational orbital-optimization scheme for the antisymmetric product of one-reference orbital geminal wave function. Our approach is motivated by the observation that an orbital-optimized seniority-zero configuration interaction (CI) expansion yields similar results to an orbital-optimized seniority-zero-plus-two CI expansion [L. Bytautas, T. M. Henderson, C. A. Jimenez-Hoyos, J. K. Ellis, and G. E. Scuseria, J. Chem. Phys. 135, 044119 (2011)]. A numerical analysis is performed for the C2 and LiF molecules, for the CH2 singlet diradical as well as for the symmetric stretching of hypothetical (linear) hydrogen chains. For these test cases, the proposed orbital-optimization protocol yields similar results to its variational orbital optimization counterpart, but prevents symmetry-breaking of molecular orbitals in most cases.

Boguslawski, Katharina; Tecmer, Pawe?; Limacher, Peter A.; Johnson, Paul A.; Ayers, Paul W.; Bultinck, Patrick; De Baerdemacker, Stijn; Van Neck, Dimitri

2014-06-01

417

Projected seniority-two orbital optimization of the antisymmetric product of one-reference orbital geminal.  

PubMed

We present a new, non-variational orbital-optimization scheme for the antisymmetric product of one-reference orbital geminal wave function. Our approach is motivated by the observation that an orbital-optimized seniority-zero configuration interaction (CI) expansion yields similar results to an orbital-optimized seniority-zero-plus-two CI expansion [L. Bytautas, T. M. Henderson, C. A. Jimenez-Hoyos, J. K. Ellis, and G. E. Scuseria, J. Chem. Phys. 135, 044119 (2011)]. A numerical analysis is performed for the C2 and LiF molecules, for the CH2 singlet diradical as well as for the symmetric stretching of hypothetical (linear) hydrogen chains. For these test cases, the proposed orbital-optimization protocol yields similar results to its variational orbital optimization counterpart, but prevents symmetry-breaking of molecular orbitals in most cases. PMID:24907997

Boguslawski, Katharina; Tecmer, Pawe?; Limacher, Peter A; Johnson, Paul A; Ayers, Paul W; Bultinck, Patrick; De Baerdemacker, Stijn; Van Neck, Dimitri

2014-06-01

418

Diagrammatic theory of transition of pendulum like systems. [orbit-orbit and spin-orbit gravitational resonance interactions  

NASA Technical Reports Server (NTRS)

Orbit-orbit and spin-orbit gravitational resonances are analyzed using the model of a rigid pendulum subject to both a time-dependent periodic torque and a constant applied torque. First, a descriptive model of passage through resonance is developed from an examination of the polynomial equation that determines the extremes of the momentum variable. From this study, a probability estimate for capture into libration is derived. Second, a lowest order solution is constructed and compared with the solution obtained from numerical integration. The steps necessary to systematically improve this solution are also discussed. Finally, the effect of a dissipative term in the pendulum equation is analyzed.

Yoder, C. F.

1979-01-01

419

Gravity and Orbits: Gravitational Force  

NSDL National Science Digital Library

This Science Object is the second of three Science Objects in the Gravity and Orbits SciPack. It investigates the variables that influence gravitational forces acting on objects. Mass is a measure of the amount of matter that makes up an object (regardless of where that object is located) and weight is a measure of the gravitational force acting on an object. The strength of the gravitational force between masses is proportional to the product of the masses and inversely proportional to the square of the distance between them. Gravity will cause all objects at the same distance from Earth's surface to fall toward Earth with the same acceleration regardless of their mass. Learning Outcomes:? Identify variables that affect the strength of the gravitational force acting between any two objects.? Provide a quantitative description of the relationship between the mass of two object and the gravitational force between them.? Provide a qualitative description of the relationship between the mass of two objects and the gravitational force between them.? Provide a quantitative description of the relationship between distance and gravitational force. ? Provide a qualitative description of the inverse square relationship.? Recognize the effect of air resistance on object falling near Earth's surface, and thus be able to explain why two objects with different masses, at the same distance from Earth's surface, will have equal accelerations if air resistance is ignored.

National Science Teachers Association (NSTA)

2006-11-01

420

Gravity and Orbits: Universal Gravitational  

NSDL National Science Digital Library

This Science Object is the first of three Science Objects in the Gravity and Orbits SciPack. It provides an understanding of gravitational forces associated with all objects that have mass. Every object exerts a gravitational force on every other object. The force is hard to detect unless at least one of the objects has a lot of mass. Any two objects will exert an equal gravitational force (in opposite directions) on one another. Gravity is the force behind the falling rain and flowing rivers, and is responsible for pulling the matter that makes up planets and stars toward their centers to form spheres. Learning Outcomes:? Identify gravity as an attractive force associated with all objects, including less intuitive examples (such as soda cans and pencils).? Recognize some examples of phenomena that are the result of Earth's gravity and objects and structures in the universe in general.? Reject the idea that Earth's gravity is an effect of air pushing down toward the surface.? Recognize that gravitational force does not require air (or any other substance) as a medium to act.? Describe gravitational force as a mutual attraction, rather than as one object pulling on another.

National Science Teachers Association (NSTA)

2006-11-01

421

Orbital Debris Observations with WFCAM  

NASA Technical Reports Server (NTRS)

The United Kingdom Infrared Telescope has been operating for 35 years on the summit of Mauna Kea as a premier Infrared astronomical facility. In its 35th year the telescope has been turned over to a new operating group consisting of University of Arizona, University of Hawaii and the LM Advanced Technology Center. UKIRT will continue its astronomical mission with a portion of observing time dedicated to orbital debris and Near Earth Object detection and characterization. During the past 10 years the UKIRT Wide Field CAMera (WFCAM) has been performing large area astronomical surveys in the J, H and K bands. The data for these surveys have been reduced by the Cambridge Astronomical Survey Unit in Cambridge, England and archived by the Wide Field Astronomy Unit in Edinburgh, Scotland. During January and February of 2014 the Wide Field CAMera (WFCAM) was used to scan through the geostationary satellite belt detecting operational satellites as well as nearby debris. Accurate photometric and astrometric parameters have been developed by CASU for each of the detections and all data has been archived by WFAU.

Bold, Matthew; Cross, Nick; Irwin, Mike; Kendrick, Richard; Kerr, Thomas; Lederer, Susan; Mann, Robert; Sutorius, Eckhard

2014-01-01

422

Extended Duration Orbiter Medical Project  

NASA Technical Reports Server (NTRS)

Biomedical issues have presented a challenge to flight physicians, scientists, and engineers ever since the advent of high-speed, high-altitude airplane flight in the 1940s. In 1958, preparations began for the first manned space flights of Project Mercury. The medical data and flight experience gained through Mercury's six flights and the Gemini, Apollo, and Skylab projects, as well as subsequent space flights, comprised the knowledge base that was used to develop and implement the Extended Duration Orbiter Medical Project (EDOMP). The EDOMP yielded substantial amounts of data in six areas of space biomedical research. In addition, a significant amount of hardware was developed and tested under the EDOMP. This hardware was designed to improve data gathering capabilities and maintain crew physical fitness, while minimizing the overall impact to the microgravity environment. The biomedical findings as well as the hardware development results realized from the EDOMP have been important to the continuing success of extended Space Shuttle flights and have formed the basis for medical studies of crew members living for three to five months aboard the Russian space station, Mir. EDOMP data and hardware are also being used in preparation for the construction and habitation of International Space Station. All data sets were grouped to be non-attributable to individuals, and submitted to NASA s Life Sciences Data Archive.

Sawin, Charles F. (Editor); Taylor, Gerald R. (Editor); Smith, Wanda L. (Editor); Brown, J. Travis (Technical Monitor)

1999-01-01

423

Orbit of the Ophiuchus Stream  

NASA Astrophysics Data System (ADS)

Ophiuchus Stream is the most recently discovered stellar stream in the Milky Way (Bernard et al. 2014). Due to its location (?5 kpc from the Galactic center) and its puzzling morphology (a thin and short stream, and yet with no visible progenitor), this stream may represent an important piece in our efforts to understand the Galactic potential and the dynamical evolution of accreted structures. In this talk, I will present a followup study of the stream during which we obtained high-quality spectroscopic data on 14 stream member stars using Keck and MMT telescopes. I will show how these newly acquired spectroscopic and existing photometric data enabled us to constrain i) the distance and line-of-sight extent of the stream, ii) the full 3D kinematics of the stream, iii) the chemical properties of the stream and the nature of its progenitor, and iv) the orbit of the stream. I will finish by discussing future prospects in this field in light of the upcoming public release of Pan-STARRS1, Palomar Transient Factory, and GAIA data.

Sesar, Branimir; Bernard, Edouard J.; Bovy, Jo; Cohen, Judith G.; Caldwell, Nelson; Ness, Melissa; Johnson, Christian I.; Ferguson, Annette M. N.; Martin, Nicolas; Rix, Hans-Walter; Ford Schlafly, Eddie; Pan-Starrs1 Collaboration

2015-01-01

424

Spacewire on Earth orbiting scatterometers  

NASA Technical Reports Server (NTRS)

The need for a high speed, reliable and easy to implement communication link has led to the development of a space flight oriented version of IEEE 1355 called SpaceWire. SpaceWire is based on high-speed (200 Mbps) serial point-to-point links using Low Voltage Differential Signaling (LVDS). SpaceWIre has provisions for routing messages between a large network of processors, using wormhole routing for low overhead and latency. {additionally, there are available space qualified hybrids, which provide the Link layer to the user's bus}. A test bed of multiple digital signal processor breadboards, demonstrating the ability to meet signal processing requirements for an orbiting scatterometer has been implemented using three Astrium MCM-DSPs, each breadboard consists of a Multi Chip Module (MCM) that combines a space qualified Digital Signal Processor and peripherals, including IEEE-1355 links. With the addition of appropriate physical layer interfaces and software on the DSP, the SpaceWire link is used to communicate between processors on the test bed, e.g. sending timing references, commands, status, and science data among the processors. Results are presented on development issues surrounding the use of SpaceWire in this environment, from physical layer implementation (cables, connectors, LVDS drivers) to diagnostic tools, driver firmware, and development methodology. The tools, methods, and hardware, software challenges and preliminary performance are investigated and discussed.

Bachmann, Alex; Lang, Minh; Lux, James; Steffke, Richard

2002-01-01

425

Liouville theory and special coadjoint Virasoro orbits  

E-print Network

We describe the Hamiltonian reduction of the coajoint Kac-Moody orbits to the Virasoro coajoint orbits explicitly in terms of the Lagrangian approach for the Wess-Zumino-Novikov-Witten theory. While a relation of the coajoint Virasoro orbit $Diff \\; S^1 /SL(2,R)$ to the Liouville theory has been already studied we analyse the role of special coajoint Virasoro orbits $Diff \\; S^1/\\tilde{T}_{\\pm ,n}$ corresponding to stabilizers generated by the vector fields with double zeros. The orbits with stabilizers with single zeros do not appear in the model. We find an interpretation of zeros $x_i$ of the vector field of stabilizer $\\tilde{T}_{\\pm ,n}$ and additional parameters $q_i$, $i = 1,...,n$, in terms of quantum mechanics for $n$ point particles on the circle. We argue that the special orbits are generated by insertions of "wrong sign" Liouville exponential into the path integral. The additional parmeters $q_i$ are naturally interpreted as accessory parameters for the uniformization map. Summing up the contributions of the special Virasoro orbits we get the integrable sinh-Gordon type theory.

A. Gorsky; A. Johansen

1993-11-09

426

Matter Waves and Orbital Quantum Numbers  

E-print Network

The atom's orbital electron structure in terms of quantum numbers (principal, azimuthal, magnetic and spin) results in space for a maximum of: 2 electrons in the n=1 orbit, 8 electrons in the n=2 orbit, 18 electrons in the n=3 orbit, and so on. Those dispositions are correct, but that is not because of quantum numbers nor angular momentum nor a "Pauli exclusion principle". Matter waves were discovered in the early 20th century from their wavelength, which was predicted by DeBroglie to be, Planck's constant divided by the particle's momentum. But, the failure to obtain a reasonable theory for the matter wave frequency resulted in loss of interest. That problem is resolved in "A Reconsideration of Matter Waves" in which a reinterpretation of Einstein's derivation of relativistic kinetic energy [which produced his famous E = mc^2] leads to a valid matter wave frequency and a new understanding of particle kinetics and the atom's stable orbits. It is analytically shown that the orbital electron arrangement is enforced by the necessity of accommodating the space that each orbiting electron's matter wave occupies.

Roger Ellman

2005-05-18

427

Toroidal path filter for orbital conjunction screening  

NASA Astrophysics Data System (ADS)

For satellite conjunction prediction containing many objects, timely processing can be a concern. Various filters are used to identify orbiting pairs that cannot come close enough over a prescribed time period to be considered hazardous. Such pairings can then be eliminated from further computation to quicken the overall processing time. One such filter is the orbit path filter (also known as the geometric pre-filter), designed to eliminate pairs of objects based on characteristics of orbital motion. The goal of this filter is to eliminate pairings where the distance (geometry) between their orbits remains above some user-defined threshold, irrespective of the actual locations of the satellites along their paths. Rather than using a single distance bound, this work presents a toroid approach, providing a measure of versatility by allowing the user to specify different in-plane and out-of-plane bounds for the path filter. The primary orbit is used to define a focus-centered elliptical ring torus with user-defined thresholds. An assessment is then made to determine if the secondary orbit can touch or penetrate this torus. The method detailed here can be used on coplanar, as well as non-coplanar, orbits.

Alfano, Salvatore

2012-07-01

428

47 CFR 25.280 - Inclined orbit operations.  

... 2014-10-01 false Inclined orbit operations. 25.280 Section 25...Technical Operations § 25.280 Inclined orbit operations. (a) Satellite operators may commence operation in inclined orbit mode without obtaining prior...

2014-10-01

429

Mission analysis data for inclined geosynchronous orbits, part 1  

NASA Technical Reports Server (NTRS)

Data needed for preliminary design of inclined geosynchronous missions are provided. The inertial and Earth fixed coordinate systems are described, as well as orbit parameters and elements. The complete family of geosynchronous orbits is discussed. It is shown that circular inclined geosynchronous orbits comprise only one set in this family. The major orbit perturbation and their separate effects on the geosynchronous orbit are discussed. Detailed information on the orbit perturbation of inclined circular geosynchronous orbits is given, with emphasis on time history data of certain orbital elements. Orbit maintenance delta velocity (V) requirements to counteract the major orbit perturbations are determined in order to provide order of magnitude estimates and to show the effects of orbit inclination on delta V. Some of the considerations in mission design for a multisatellite system, such as a halo orbit constellation, are discussed.

Graf, O. F., Jr.; Wang, K. C.

1980-01-01

430

Preliminary orbit determination by static multivariate search  

NASA Astrophysics Data System (ADS)

A static multivariate search algorithm based on the Gram-Schmidt method is used for the problem of preliminary orbit determination using tracking data covering a very short arc of the orbit and very approximate initial estimate. The method is based on orthogonalization to find the primary and secondary search directions. No partial derivatives are needed. The extremum is found by parabolic extrapolation or interpolation of the function values. The suitability and effectiveness of the method for the problem of preliminary orbit determination is demonstrated. The approach yields desirable accuracies in simulated tracking data and application to actual tracking data of Indian satellites BHASKARA-2 APPLE and INSAT 1-A.

Rajendraprasad, P.; Gopinath, N. S.; Bhat, R. S.

431

Aggressive glabellar angiomyxoma with orbital extension.  

PubMed

A 62-year-old male presented with a large non-tender mass in the glabella, extending into the right orbit that had been steadily growing for 6 months. Imaging revealed a 2.5 x 1.8?cm cystic mass with extension into the right anterior orbit. Biopsy with microscopic examination revealed a predominantly myxoid stroma containing spindle-shaped cells with bipolar cigar-shaped nuclei and small caliber capillary-type vascular proliferations. These findings are consistent with an angiomyxoma. Although angiomyxomas typically present in the pelvic region or peritoneum in female patients, there have been rare examples of angiomyxomas with orbital involvement. PMID:22974117

Mishulin, Aleksey; Lever, Jackson F; Porter, William; Servat, Juan Javier; Gladstone, Geoffrey; Black, Evan

2012-10-01

432

Machine vision for real time orbital operations  

NASA Technical Reports Server (NTRS)

Machine vision for automation and robotic operation of Space Station era systems has the potential for increasing the efficiency of orbital servicing, repair, assembly and docking tasks. A machine vision research project is described in which a TV camera is used for inputing visual data to a computer so that image processing may be achieved for real time control of these orbital operations. A technique has resulted from this research which reduces computer memory requirements and greatly increases typical computational speed such that it has the potential for development into a real time orbital machine vision system. This technique is called AI BOSS (Analysis of Images by Box Scan and Syntax).

Vinz, Frank L.

1988-01-01

433

Evolution of asteroidal orbits with high inclinations  

NASA Astrophysics Data System (ADS)

The 20,000 years orbital evolution of massless fictitious asteroid located at a border of the Hill's gravitational sphere has been investigated. The eleven orbits with the eccentricities from 0.0 to 0.4 in five groups of inclinations from 40 deg to 80 deg were numerically integrated with planetary perturbations of six major planets, using the numerical integration n-body program with the Everhart's integrator RA 15. For each group time evolution of orbital elements of the asteroids is presented.

Solovaya, Nina A.; Pittich, Eduard M.

1993-10-01

434

The orbital mechanics of flight mechanics  

NASA Technical Reports Server (NTRS)

A reference handbook on modern dynamic orbit theory is presented. Starting from the most basic inverse-square law, the law of gravity for a sphere is developed, and the motion of point masses under the influence of a sphere is considered. The reentry theory and the orbital theory are discussed along with the relative motion between two bodies in orbit about the same planet. Relative-motion equations, rectangular coordinates, and the mechanics of simple rigid bodies under the influence of a gravity gradient field are also discussed.

Dunning, R. S.

1973-01-01

435

The Orbital Gyromagnetic Factor of Relativistic Electrons  

NASA Astrophysics Data System (ADS)

An analog of the Bargmann-Michel-Telegdi (BMT) equation which describes the motion of the spin four-vector S is derived for the orbital magnetic moment L. It is shown that in addition to the term in dL/dt describing the precession of the orbital angular momentum in a magnetic field, there appears a term which may imply the possibility of an anomalous contribution to the orbital g-factor gL. Experiments to measure the anomaly are discussed. )

Awobode, Ayodeji

2010-02-01

436

THE PYTHON SHELL FOR THE ORBIT CODE  

SciTech Connect

A development of a Python driver shell for the ORBIT simulation code is presented. The original ORBIT code uses the SuperCode shell to organize accelerator-related simulations. It is outdated, unsupported, and it is an obstacle to future code development. The necessity and consequences of replacing the old shell language are discussed. A set of core modules and extensions that are currently in PyORBIT are presented. They include particle containers, parsers for MAD and SAD lattice files, a Python wrapper for MPI libraries, space charge calculators, TEAPOT trackers, and a laser stripping extension module.

Shishlo, Andrei P [ORNL] [ORNL; Gorlov, Timofey V [ORNL] [ORNL; Holmes, Jeffrey A [ORNL] [ORNL

2009-01-01

437

Lateral orbital expansion and gradual fronto-orbital advancement: an option to treat severe syndromic craniosynostosis.  

PubMed

In some patients with severe syndromic craniosynostosis, bony orbits are so small and shallow that the eyeballs dislocate. Dry cornitis and conjunctivitis can be seen often. When conventional fronto-orbital advancement is attempted in these cases, side walls of the orbit cannot go forward, because the width of bony orbit is smaller than the eyeball. To expand bony orbits and cranial volume, supralateral rim of the orbit was expanded laterally at the time of operation and gradually advanced foward postoperatively. With a coronal skin incision approach, frontal bone was taken off. Supralateral orbital rim bone was detached and cut at the centers of the orbits. Lateral expansion, 5 to 10 mm, was made and fixed with polylactate plates. A pair of distraction devices was fixed between the orbital rim and the temporal bone. Frontal bone was let floating on the dura mater and tied loosely with the orbital rim. Advancement of 1 to 1.5 mm/d was carried out, and the devices were taken off after 1-month consolidation period. Five patients with Pfeiffer syndrome, 1 with Crouzon, and 1 with Beare-Stevenson cutis gyrata syndrome were treated with this method. Procedure, outcomes, and complications are discussed. PMID:19098565

Nishimoto, Soh; Oyama, Tomoki; Nagashima, Tatsuya; Osaki, Yoko; Yoshimura, Yuki; Fukuda, Kenji; Kawai, Kenichiro; Tsumano, Tomoko; Kakibuchi, Masao

2008-11-01

438

The Carter Constant for Inclined Orbits About a Massive Kerr Black Hole: I. circular orbits  

E-print Network

In an extreme binary black hole system, an orbit will increase its angle of inclination (i) as it evolves in Kerr spacetime. We focus our attention on the behaviour of the Carter constant (Q) for near-polar orbits; and develop an analysis that is independent of and complements radiation reaction models. For a Schwarzschild black hole, the polar orbits represent the abutment between the prograde and retrograde orbits at which Q is at its maximum value for given values of latus rectum (l) and eccentricity (e). The introduction of spin (S = |J|/M2) to the massive black hole causes this boundary, or abutment, to be moved towards greater orbital inclination; thus it no longer cleanly separates prograde and retrograde orbits. To characterise the abutment of a Kerr black hole (KBH), we first investigated the last stable orbit (LSO) of a test-particle about a KBH, and then extended this work to general orbits. To develop a better understanding of the evolution of Q we developed analytical formulae for Q in terms of l, e, and S to describe elliptical orbits at the abutment, polar orbits, and last stable orbits (LSO). By knowing the analytical form of dQ/dl at the abutment, we were able to test a 2PN flux equation for Q. We also used these formulae to numerically calculate the di/dl of hypothetical circular orbits that evolve along the abutment. From these values we have determined that di/dl = -(122.7S - 36S^3)l^-11/2 -(63/2 S + 35/4 S^3) l^-9/2 -15/2 S l^-7/2 -9/2 S l^-5/2. Thus the abutment becomes an important analytical and numerical laboratory for studying the evolution of Q and i in Kerr spacetime and for testing current and future radiation back-reaction models for near-polar retrograde orbits.

P. G. Komorowski; S. R. Valluri; M. Houde

2011-01-19

439

Orbital Transfer Vehicle (space taxi) with aerobraking at Earth and Mars  

NASA Technical Reports Server (NTRS)

This report shall cover all major aspects of the design of an Aeroassisted Manned Transfer Vehicle (or TAXI) for use as part of advanced manned Mars missions based on a cycling ship concept. Along with the heliocentric orbiting Cycling Spacecraft, such a TAXI would be a primary component of a long-term transportation system for Mars exploration. The Aeroassisted Manned Transfer Vehicle (AMTV) design developed shall operate along transfer trajectories between Earth and a Cycling Spacecraft (designed by the University of Michigan) and Mars. All operations of the AMTV shall be done primarily within the sphere of influence of the two planets. Maximum delta-V's for the vehicle have been established near 9 km/sec, with transfer durations of about 3 days. Acceleration deltaV's will be accomplished using 3 SSME-based hydrogen-oxygen chemical rockets (l(sub sp) = 485 sec & Thrust greater than = 300,00 Ib(sub f)/engine) with a thrust vector directly opposite the aerobraking deceleration vector. The aerobraking deceleration portion of an AMTV mission would be accomplished in this design by a moderate L/D aeroshield of an ellipsoidally-blunt, raked-off, elliptic cone (EBROEC) shape. The reusable thermal protection material comprising the shield will consist of a flexible, multi-layer, ceramic fabric stretched over a lightweight, rigid, shape - defining truss structure. Behind this truss, other components, including the engine supports, would be attached and protected from heating during aerobraking passes. Among these other components would be 2 LOX tanks and 4 LH2 tanks (and their support frames) holding over 670,000 lbm of propellant necessary to impart the required delta-V to the 98,000 lbm burnout mass vehicle. A 20,000 lbm crew module with docking port (oriented parallel to the accel./decel. axis) will provide accommodations for 9 crew members (11 under extreme conditions) for durations up to seven days, thus allowing extra time for emergency situations. This AMTV will be equipped with complete guidance, navigation, control and communications systems modules attached near the crew module. Control of vehicle attitude will be provided by a set of small reaction control thrusters quite similar to those on the current Space Shuttle. All crew module and vehicle electrical functions will be powered via a set of H2/O2 fuel cells with radio-isotopic generators as backup supplies. Also included in the burnout mass of 98,000 lb is allowance for 10,000 lbm of miscellaneous payload (scientific equipment or other supplies).

1987-01-01

440

STS mission duration enhancement study: (orbiter habitability)  

NASA Technical Reports Server (NTRS)

Habitability improvements for early flights that could be implemented with minimum impact were investigated. These included: (1) launching the water dispenser in the on-orbit position instead of in a locker; (2) the sleep pallet concept; and (3) suction cup foot restraints. Past studies that used volumetric terms and requirements for crew size versus mission duration were reviewed and common definitions of key habitability terms were established. An accurately dimensioned drawing of the orbiter mid-deck, locating all of the known major elements was developed. Finally, it was established that orbiter duration and crew size can be increased with minimum modification and impact to the crew module. Preliminary concepts of the aft med-deck, external versions of expanded tunnel adapters (ETA), and interior concepts of ETA-3 were developed and comparison charts showing the various factors of volume, weight, duration, size, impact to orbiter, and number of sleep stations were generated.

Carlson, A. D.

1979-01-01

441

Modal control of an unstable periodic orbit  

NASA Technical Reports Server (NTRS)

Floquet theory is applied to the problem of designing a control system for a satellite in an unstable periodic orbit. Expansion about a periodic orbit produces a time-periodic linear system, which is augmented by a time-periodic control term. It is shown that this can be done such that (1) the application of control produces only inertial accelerations, (2) positive real Poincareexponents are shifted into the left half-plane, and (3) the shift of the exponent is linear with control gain. These developments are applied to an unstable orbit near the earth-moon L(3) point pertubed by the sun. Finally, it is shown that the control theory can be extended to include first order perturbations about the periodic orbit without increase in control cost.

Wiesel, W.; Shelton, W.

1983-01-01

442

First-principles theory of orbital magnetization  

E-print Network

Within density-functional theory we compute the orbital magnetization for periodic systems evaluating a recently discovered Berry-phase formula. For the ferromagnetic metals Fe, Co, and Ni we explicitly calculate the ...

Gerstmann, Uwe

443

Online Short Course: Gravity and Orbits  

NSDL National Science Digital Library

What's holding you down? Join us for the new NSTA Online Short Course: Gravity and Orbits and find out! This short course will explore concepts related to Earth's universal gravitation and how gravity affects the universe arou

1900-01-01

444

Spinning compact binary dynamics and chameleon orbits  

E-print Network

We analyse the conservative evolution of spinning compact binaries to second post-Newtonian (2PN) order accuracy, with leading order spin-orbit, spin-spin and mass quadrupole-monopole contributions included. As a main result we derive a closed system of first order differential equations in a compact form, for a set of dimensionless variables encompassing both orbital elements and spin angles. These evolutions are constrained by conservation laws holding at 2PN order. As required by the generic theory of constrained dynamical systems we perform a consistency check and prove that the constraints are preserved by the evolution. We apply the formalism to show the existence of chameleon orbits, whose local, orbital parameters evolve from elliptic (in the Newtonian sense) near pericenter, towards hyperbolic at large distances. This behavior is consistent with the picture that General Relativity predicts stronger gravity at short distances than Newtonian theory does.

László Árpád Gergely; Zoltán Keresztes

2014-11-14

445

Orbiter active thermal control system description  

NASA Technical Reports Server (NTRS)

A brief description of the Orbiter Active Thermal Control System (ATCS) including (1) major functional requirements of heat load, temperature control and heat sink utilization, (2) the overall system arrangement, and (3) detailed description of the elements of the ATCS.

Laubach, G. E.

1975-01-01

446

The Shuttle Orbiter Airlock Support Subsystem /ALSS/  

NASA Technical Reports Server (NTRS)

The Orbiter Airlock Support Subsystem (ALSS) is designed to provide shirtsleeve intervehicular transfer (IVA) between the orbiter and payload spacelab. Also, the airlock provides for extravehicular transfer (EVA) of two crewman to space and/or unpressurized payload from a pressurized cabin environment. The orbiter airlock design permits three planned EVA's for periods up to 6 hr. The airlock is designed to be interchangeable in three different locations, in the crew cabin, attached to the cabin aft bulkhead or attached to transfer tunnel adapter both which are located in the cargo bay. The Orbiter Airlock Support Subsystem described herein provides ventilation, pressurization, depressurization, prebreathing, personnel oxygen system supply (POS), and Extravehicular Mobility Unit support (EMU). This paper defines the system configuration for each airlock location and the commonality between them. Emphasis is also placed on the design data used to define repressurization and depressurization requirements, ventilation, water cooling, wastewater discharge, flow rates, and valve sizing.

Brown, J. T.; Martin, D.; Stoll, O. T.

1976-01-01

447

Improved formulas for calculating cyclotron orbit properties  

NASA Astrophysics Data System (ADS)

Using improved techniques, analytical formulas are derived for calculating the orbit period, the radial tune, and the vertical tune as a function of energy for a given magnetic field. As examples, these formulas are applied to fields from two different machines: the three-sector K1200 superconducting cyclotron at this laboratory, and the six-sector 500 MeV cyclotron at the TRIUMF laboratory. A comparison of the results with those from a standard orbit integration program shows that the analytical formulas are, on the average, highly accurate for the orbit period, quite accurate for the radial tune, but only moderately accurate for the vertical tune. Moreover, differences between the theoretical and orbit code results are found to exhibit relatively large fluctuations which are produced by small irregularities in the measured field data.

Gordon, M. M.; Jeon, Dong-O

1991-03-01

448

The Orbits of the Inner Uranian Satellites  

NASA Astrophysics Data System (ADS)

We report on the numerically integrated orbits for the thirteen inner Uranian satellites. Our dataset includes Voyager imaging data as well as HST and Earth-based astrometric data. The observations span time period from 1985 to 2003. Our model of the inner moons' orbits accounts for the equatorial bulge of Uranus, the perturbations from the external bodies and the perturbations from the large moons of Uranus (Miranda, Umbriel, Ariel, Oberon, and Titania). The inner satellites were initially considered massless, but we found that this assumption may need to be revised in order to fine-tune the system's dynamics and obtain the orbital solutions with adequate residuals.The results are given in terms of state vectors,post-fit residuals and mean orbital elements.

Brozovic, Marina; Jacobson, R. A.

2009-05-01

449

Genesis Halo Orbit Station Keeping Design  

NASA Technical Reports Server (NTRS)

As the fifth mission of NASA's Directory Program, Genesis is designed to collect solar wind samples for approximately two years in a halo orbit near the Sun-Earth L(sub 1) Lagrange point for return to the Earth.

Lo, M.; Williams, K.; Wilson, R.; Howell, K.; Barden, B.

2000-01-01

450

Orbiting quarantine facility. The Antaeus report  

NASA Technical Reports Server (NTRS)

A mission plan for the Orbiting Quarantine Facility (OQF) is presented. Coverage includes system overview, quarantine and protocol, the laboratory, support systems, cost analysis and possible additional uses of the OQF.

Devincenzi, D. L. (editor); Bagby, J. R. (editor)

1981-01-01

451

Spacetime and orbits of bumpy black holes  

E-print Network

Our Universe contains a great number of extremely compact and massive objects which are generally accepted to be black holes. Precise observations of orbital motion near candidate black holes have the potential to determine ...

Vigeland, Sarah Jane

452

ORION: A Supersynchronous Transfer Orbit mission  

NASA Technical Reports Server (NTRS)

ORION F1 was launched on 29th November 1994 on an Atlas IIA launch vehicle. It was designed, built and delivered in-orbit by Matra Marconi Space Systems Plc and was handed over to ORION Satellite Corporation on 20th January 1995 at its on-station longitude of 37.5 deg W. The mission differed significantly from that of any other geostationary communications satellite in that the Transfer Orbit apogee altitude of 123,507 km was over three times geosynchronous (GEO) altitude and one third of the way to the moon. The SuperSynchronous Transfer Orbit (SSTO) mission is significantly different from the standard Geostationary Transfer Orbit (GTO)mission in a number of ways. This paper discusses the essential features of the mission design through its evolution since 1987 and the details of the highly successful mission itself including a detailed account of the attitude determination achieved using the Galileo Earth and Sun Sensor (ESS).

Walters, I. M.; Baker, J. F.; Shurmer, I. M.

1995-01-01

453

Mycosis fungoides metastatic to the orbit.  

PubMed

We report a case of mycosis fungoides metastatic to the anterior orbit in an 83-year-old woman. The patient had a history of several years' duration of well-controlled primary mycosis fungoides with localized dermatologic T-cell lymphomas, mainly on the lower extremities. She developed gradual proptosis, hyperophthalmos, and vertical diplopia. Computed tomography demonstrated a solid, extraconal mass in the right lower anterior orbit. Biopsy revealed a gristly, yellowish, infiltrating mass at the level of the inferior orbital septum. Pathologic examination revealed anaplastic T lymphocytes with multiloculated, cerebriform nuclei that matched those of the primary mycosis fungoides skin tumors. Mycosis fungoides rarely spreads to the ocular and periocular structures, and this case was unique in that it presented as a pure orbital lesion with sparing of the overlying lids and adnexal structures. PMID:2025172

Zucker, J L; Doyle, M F

1991-05-01

454

Circulating transportation orbits between earth and Mars  

NASA Technical Reports Server (NTRS)

This paper describes the basic characteristics of circulating (cyclical) orbit design as applied to round-trip transportation of crew and materials between earth and Mars in support of a sustained manned Mars Surface Base. The two main types of nonstopover circulating trajectories are the socalled VISIT orbits and the Up/Down Escalator orbits. Access to the large transportation facilities placed in these orbits is by way of taxi vehicles using hyperbolic rendezvous techniques during the successive encounters with earth and Mars. Specific examples of real trajectory data are presented in explanation of flight times, encounter frequency, hyperbolic velocities, closest approach distances, and Delta V maneuver requirements in both interplanetary and planetocentric space.

Friedlander, A. L.; Niehoff, J. C.; Byrnes, D. V.; Longuski, J. M.

1986-01-01

455

Dacryocystography in a cat with orbital pneumatosis.  

PubMed

A 2-year-old neutered male European short-haired cat was presented for a persistent discharge from the scar of previous left eye enucleation, performed 6 months prior by the referring veterinarian. A surgical exploration of the orbit was performed and retained nictitating membrane glandular and conjunctival tissues were removed. Eleven days later, the cat developed an orbital pneumatosis caused by retrograde movement of air through a patent nasolacrimal system and diagnosed by survey radiographic examination of the skull. Nasolacrimal system patency was assessed by dacryocystography performed by injection of iodinated contrast medium under pressure into the orbital cavity. Computed tomography dacryocystography confirmed the radiographic findings. The condition resolved following dacryocystography, possibly as an inflammatory response to the contrast medium. To our knowledge, this is the first case of orbital pneumatosis reported in a cat. PMID:24118801

Meomartino, Leonardo; Pasolini, Maria P; Lamagna, Francesco; Santangelo, Bruna; Mennonna, Giuseppina; Della Valle, Giovanni; Lamagna, Barbara

2013-10-14

456

ORION: A Supersynchronous Transfer Orbit mission  

NASA Astrophysics Data System (ADS)

ORION F1 was launched on 29th November 1994 on an Atlas IIA launch vehicle. It was designed, built and delivered in-orbit by Matra Marconi Space Systems Plc and was handed over to ORION Satellite Corporation on 20th January 1995 at its on-station longitude of 37.5 deg W. The mission differed significantly from that of any other geostationary communications satellite in that the Transfer Orbit apogee altitude of 123,507 km was over three times geosynchronous (GEO) altitude and one third of the way to the moon. The SuperSynchronous Transfer Orbit (SSTO) mission is significantly different from the standard Geostationary Transfer Orbit (GTO)mission in a number of ways. This paper discusses the essential features of the mission design through its evolution since 1987 and the details of the highly successful mission itself including a detailed account of the attitude determination achieved using the Galileo Earth and Sun Sensor (ESS).

Walters, I. M.; Baker, J. F.; Shurmer, I. M.

1995-05-01

457

Orbital impacts and the Space Shuttle windshield  

NASA Technical Reports Server (NTRS)

The Space Transportation System (STS) fleet has flown more than sixty missions over the fourteen years since its first flight. As a result of encounters with on-orbit particulates (space debris and micrometeoroids), 177 impact features (chips) have been found on the STS outer windows (through STS-65). Forty-five of the damages were large enough to warrant replacement of the window. NASA's orbital operations and vehicle inspection procedures have changes over the history of the shuttle program, in response to concerns about the orbital environment and the cost of maintaining the space shuttle. These programmatic issues will be discussed, including safety concerns, maintenance issues, inspection procedures and flight rule changes. Examples of orbital debris impacts to the shuttle windows will be provided. There will also be a brief discussion of the impact properties of glass and what design changes have been considered to improve the impact properties of the windows.

Edelstein, Karen S.

1995-01-01

458

Orbital debris : drafting, negotiating, implementing a convention  

E-print Network

It is time to recognize that while space may be infinite, Earth orbital space is a finite natural resource that must be managed properly. The problem we face with space pollution is complex and serious. The space treaties ...

Sénéchal, Thierry

2007-01-01

459

NASA-GSFC Orbital Debris Research Priorities  

NASA Technical Reports Server (NTRS)

While quite a lot is known about the orbital debris environment and how to limit its growth, more remains to be learned. The curent priorities for research and development, from the NASA Goddard Space Flight Center perspective, will be discussed.

Hull, Scott M.

2014-01-01

460

Spinning compact binary dynamics and chameleon orbits  

NASA Astrophysics Data System (ADS)

We analyze the conservative evolution of spinning compact binaries to second post-Newtonian (2PN) order accuracy, with leading-order spin-orbit, spin-spin and mass quadrupole-monopole contributions included. As a main result we derive a closed system of first-order differential equations in a compact form, for a set of dimensionless variables encompassing both orbital elements and spin angles. These evolutions are constrained by conservation laws holding at 2PN order. As required by the generic theory of constrained dynamical systems we perform a consistency check and prove that the constraints are preserved by the evolution. We apply the formalism to show the existence of chameleon orbits, whose local, orbital parameters evolve from elliptic (in the Newtonian sense) near pericenter, towards hyperbolic at large distances. This behavior is consistent with the picture that general relativity predicts stronger gravity at short distances than Newtonian theory does.

Gergely, László Árpád; Keresztes, Zoltán

2015-01-01

461

Probe theory - the orbital motion approach  

Microsoft Academic Search

A review is given of the orbital motion limited (O.M.L.) theory of cylindrical and spherical Langmuir probes. In many cases the O.M.L. theory is invalid and the second orbital motion theory presented here, that of Bohm, Burhop and Massey, shows that the concept of an absorption radius must be introduced. The extensive numerical extensions to this theory are briefly discussed.Recent

J E Allen

1992-01-01

462

Advanced propulsion concepts for orbital transfer vehicles  

NASA Technical Reports Server (NTRS)

Studies of the United States Space Transportation System show that in the mid-to-late 1990s expanded capabilities for Orbital Transfer Vehicles (OTV) will be needed to meet increased payload requirements for transporting materials and possible men to geosynchronous orbit. NASA is conducting a technology program in support of an advanced propulsion system for future OTVs. This program is briefly described with results to date of the first program element, the Conceptual Design and Technology Definition studies.

Cooper, L. P.

1982-01-01

463

Rhino-Orbital Mucormycosis in Diabetes Mellitus  

PubMed Central

Rhino-orbital mucormycosis is a rare but life threatening infection that generally occurs in patients with diabetes mellitus and other immune deficiency conditions. Rhino-orbital and Rhino-cerebral are two form of the disease. As such the condition is a medical emergency. Early recognition and treatment are essential because it may lead to death in few days. Fungal infection of nasal cavity is uncommon but is being seen with increasing frequency in patients with immune deficiency. PMID:23905123

Shinde, Ravindra V.; Karande, Geeta S.; Mohite, S.T.; Patil, S.R.

2013-01-01

464

LANDSAT-5 orbit adjust maneuver report  

NASA Technical Reports Server (NTRS)

The orbit adjust maneuvers performed to raise the LANDSAT 5 spacecraft to mission altitude, synchronize it with the required groundtrack, and properly phase the spacecraft with LANDSAT-4 to provide an 8 day full Earth coverage cycle are described. Maneuver planning and evaluation procedures, data and analysis results for all maneuvers performed to date, the frozen orbit concept, and the phasing requirement between LANDSAT-4 and LANDSAT-5 are also examined.

Hassett, P. J.; Johnson, R. L.

1984-01-01

465

Introduction to orbital flight planning (1)  

NASA Technical Reports Server (NTRS)

This workbook is designed for students interested in space flight planning, who after training, may serve as flight planning aides. Routine flight planning activities requiring engineering-type calculations and analysis are covered. Practice exercises and brief instructions are given for the programming and use of the hand calculator as well as the calculation of position and velocity in the orbital plane. Calculation of relative orbital position is also covered with emphasis upon celestial coordinates and time measurement.

Blackwell, H. E. (editor); Davis, E. L.; Dell, D. D.

<